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  • ANTS CLR and Memory Profiler In Depth Review (Part 1 of 2 &ndash; CLR Profiler)

    - by ToStringTheory
    One of the things that people might not know about me, is my obsession to make my code as efficient as possible.  Many people might not realize how much of a task or undertaking that this might be, but it is surely a task as monumental as climbing Mount Everest, except this time it is a challenge for the mind…  In trying to make code efficient, there are many different factors that play a part – size of project or solution, tiers, language used, experience and training of the programmer, technologies used, maintainability of the code – the list can go on for quite some time. I spend quite a bit of time when developing trying to determine what is the best way to implement a feature to accomplish the efficiency that I look to achieve.  One program that I have recently come to learn about – Red Gate ANTS Performance (CLR) and Memory profiler gives me tools to accomplish that job more efficiently as well.  In this review, I am going to cover some of the features of the ANTS profiler set by compiling some hideous example code to test against. Notice As a member of the Geeks With Blogs Influencers program, one of the perks is the ability to review products, in exchange for a free license to the program.  I have not let this affect my opinions of the product in any way, and Red Gate nor Geeks With Blogs has tried to influence my opinion regarding this product in any way. Introduction The ANTS Profiler pack provided by Red Gate was something that I had not heard of before receiving an email regarding an offer to review it for a license.  Since I look to make my code efficient, it was a no brainer for me to try it out!  One thing that I have to say took me by surprise is that upon downloading the program and installing it you fill out a form for your usual contact information.  Sure enough within 2 hours, I received an email from a sales representative at Red Gate asking if she could help me to achieve the most out of my trial time so it wouldn’t go to waste.  After replying to her and explaining that I was looking to review its feature set, she put me in contact with someone that setup a demo session to give me a quick rundown of its features via an online meeting.  After having dealt with a massive ordeal with one of my utility companies and their complete lack of customer service, Red Gates friendly and helpful representatives were a breath of fresh air, and something I was thankful for. ANTS CLR Profiler The ANTS CLR profiler is the thing I want to focus on the most in this post, so I am going to dive right in now. Install was simple and took no time at all.  It installed both the profiler for the CLR and Memory, but also visual studio extensions to facilitate the usage of the profilers (click any images for full size images): The Visual Studio menu options (under ANTS menu) Starting the CLR Performance Profiler from the start menu yields this window If you follow the instructions after launching the program from the start menu (Click File > New Profiling Session to start a new project), you are given a dialog with plenty of options for profiling: The New Session dialog.  Lots of options.  One thing I noticed is that the buttons in the lower right were half-covered by the panel of the application.  If I had to guess, I would imagine that this is caused by my DPI settings being set to 125%.  This is a problem I have seen in other applications as well that don’t scale well to different dpi scales. The profiler options give you the ability to profile: .NET Executable ASP.NET web application (hosted in IIS) ASP.NET web application (hosted in IIS express) ASP.NET web application (hosted in Cassini Web Development Server) SharePoint web application (hosted in IIS) Silverlight 4+ application Windows Service COM+ server XBAP (local XAML browser application) Attach to an already running .NET 4 process Choosing each option provides a varying set of other variables/options that one can set including options such as application arguments, operating path, record I/O performance performance counters to record (43 counters in all!), etc…  All in all, they give you the ability to profile many different .Net project types, and make it simple to do so.  In most cases of my using this application, I would be using the built in Visual Studio extensions, as they automatically start a new profiling project in ANTS with the options setup, and start your program, however RedGate has made it easy enough to profile outside of Visual Studio as well. On the flip side of this, as someone who lives most of their work life in Visual Studio, one thing I do wish is that instead of opening an entirely separate application/gui to perform profiling after launching, that instead they would provide a Visual Studio panel with the information, and integrate more of the profiling project information into Visual Studio.  So, now that we have an idea of what options that the profiler gives us, its time to test its abilities and features. Horrendous Example Code – Prime Number Generator One of my interests besides development, is Physics and Math – what I went to college for.  I have especially always been interested in prime numbers, as they are something of a mystery…  So, I decided that I would go ahead and to test the abilities of the profiler, I would write a small program, website, and library to generate prime numbers in the quantity that you ask for.  I am going to start off with some terrible code, and show how I would see the profiler being used as a development tool. First off, the IPrimes interface (all code is downloadable at the end of the post): interface IPrimes { IEnumerable<int> GetPrimes(int retrieve); } Simple enough, right?  Anything that implements the interface will (hopefully) provide an IEnumerable of int, with the quantity specified in the parameter argument.  Next, I am going to implement this interface in the most basic way: public class DumbPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _analyzing = 4; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; //start dividing at 2 //divide until number is reached, or determined not prime for (int i = 2; i < _analyzing && isPrime; i++) { //if (i) goes into _analyzing without a remainder, //_analyzing is NOT prime if (_analyzing % i == 0) isPrime = false; } //if it is prime, add to found list if (isPrime) _foundPrimes.Add(_analyzing); //increment number to analyze next _analyzing++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } This is the simplest way to get primes in my opinion.  Checking each number by the straight definition of a prime – is it divisible by anything besides 1 and itself. I have included this code in a base class library for my solution, as I am going to use it to demonstrate a couple of features of ANTS.  This class library is consumed by a simple non-MVVM WPF application, and a simple MVC4 website.  I will not post the WPF code here inline, as it is simply an ObservableCollection<int>, a label, two textbox’s, and a button. Starting a new Profiling Session So, in Visual Studio, I have just completed my first stint developing the GUI and DumbPrimes IPrimes class, so now I want to check my codes efficiency by profiling it.  All I have to do is build the solution (surprised initiating a profiling session doesn’t do this, but I suppose I can understand it), and then click the ANTS menu, followed by Profile Performance.  I am then greeted by the profiler starting up and already monitoring my program live: You are provided with a realtime graph at the top, and a pane at the bottom giving you information on how to proceed.  I am going to start by asking my program to show me the first 15000 primes: After the program finally began responding again (I did all the work on the main UI thread – how bad!), I stopped the profiler, which did kill the process of my program too.  One important thing to note, is that the profiler by default wants to give you a lot of detail about the operation – line hit counts, time per line, percent time per line, etc…  The important thing to remember is that this itself takes a lot of time.  When running my program without the profiler attached, it can generate the 15000 primes in 5.18 seconds, compared to 74.5 seconds – almost a 1500 percent increase.  While this may seem like a lot, remember that there is a trade off.  It may be WAY more inefficient, however, I am able to drill down and make improvements to specific problem areas, and then decrease execution time all around. Analyzing the Profiling Session After clicking ‘Stop Profiling’, the process running my application stopped, and the entire execution time was automatically selected by ANTS, and the results shown below: Now there are a number of interesting things going on here, I am going to cover each in a section of its own: Real Time Performance Counter Bar (top of screen) At the top of the screen, is the real time performance bar.  As your application is running, this will constantly update with the currently selected performance counters status.  A couple of cool things to note are the fact that you can drag a selection around specific time periods to drill down the detail views in the lower 2 panels to information pertaining to only that period. After selecting a time period, you can bookmark a section and name it, so that it is easy to find later, or after reloaded at a later time.  You can also zoom in, out, or fit the graph to the space provided – useful for drilling down. It may be hard to see, but at the top of the processor time graph below the time ticks, but above the red usage graph, there is a green bar. This bar shows at what times a method that is selected in the ‘Call tree’ panel is called. Very cool to be able to click on a method and see at what times it made an impact. As I said before, ANTS provides 43 different performance counters you can hook into.  Click the arrow next to the Performance tab at the top will allow you to change between different counters if you have them selected: Method Call Tree, ADO.Net Database Calls, File IO – Detail Panel Red Gate really hit the mark here I think. When you select a section of the run with the graph, the call tree populates to fill a hierarchical tree of method calls, with information regarding each of the methods.   By default, methods are hidden where the source is not provided (framework type code), however, Red Gate has integrated Reflector into ANTS, so even if you don’t have source for something, you can select a method and get the source if you want.  Methods are also hidden where the impact is seen as insignificant – methods that are only executed for 1% of the time of the overall calling methods time; in other words, working on making them better is not where your efforts should be focused. – Smart! Source Panel – Detail Panel The source panel is where you can see line level information on your code, showing the code for the currently selected method from the Method Call Tree.  If the code is not available, Reflector takes care of it and shows the code anyways! As you can notice, there does seem to be a problem with how ANTS determines what line is the actual line that a call is completed on.  I have suspicions that this may be due to some of the inline code optimizations that the CLR applies upon compilation of the assembly.  In a method with comments, the problem is much more severe: As you can see here, apparently the most offending code in my base library was a comment – *gasp*!  Removing the comments does help quite a bit, however I hope that Red Gate works on their counter algorithm soon to improve the logic on positioning for statistics: I did a small test just to demonstrate the lines are correct without comments. For me, it isn’t a deal breaker, as I can usually determine the correct placements by looking at the application code in the region and determining what makes sense, but it is something that would probably build up some irritation with time. Feature – Suggest Method for Optimization A neat feature to really help those in need of a pointer, is the menu option under tools to automatically suggest methods to optimize/improve: Nice feature – clicking it filters the call tree and stars methods that it thinks are good candidates for optimization.  I do wish that they would have made it more visible for those of use who aren’t great on sight: Process Integration I do think that this could have a place in my process.  After experimenting with the profiler, I do think it would be a great benefit to do some development, testing, and then after all the bugs are worked out, use the profiler to check on things to make sure nothing seems like it is hogging more than its fair share.  For example, with this program, I would have developed it, ran it, tested it – it works, but slowly. After looking at the profiler, and seeing the massive amount of time spent in 1 method, I might go ahead and try to re-implement IPrimes (I actually would probably rewrite the offending code, but so that I can distribute both sets of code easily, I’m just going to make another implementation of IPrimes).  Using two pieces of knowledge about prime numbers can make this method MUCH more efficient – prime numbers fall into two buckets 6k+/-1 , and a number is prime if it is not divisible by any other primes before it: public class SmartPrimes : IPrimes { public IEnumerable<int> GetPrimes(int retrieve) { //store a list of primes already found var _foundPrimes = new List<int>() { 2, 3 }; //if i ask for 1 or two primes, return what asked for if (retrieve <= _foundPrimes.Count()) return _foundPrimes.Take(retrieve); //the next number to look at int _k = 1; //since I already determined I don't have enough //execute at least once, and until quantity is sufficed do { //assume prime until otherwise determined bool isPrime = true; int potentialPrime; //analyze 6k-1 //assign the value to potential potentialPrime = 6 * _k - 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); if (_foundPrimes.Count() == retrieve) break; //analyze 6k+1 //assign the value to potential potentialPrime = 6 * _k + 1; //if there are any primes that divise this, it is NOT a prime number //using PLINQ for quick boost isPrime = !_foundPrimes.AsParallel() .Any(prime => potentialPrime % prime == 0); //if it is prime, add to found list if (isPrime) _foundPrimes.Add(potentialPrime); //increment k to analyze next _k++; } while (_foundPrimes.Count() < retrieve); return _foundPrimes; } } Now there are definitely more things I can do to help make this more efficient, but for the scope of this example, I think this is fine (but still hideous)! Profiling this now yields a happy surprise 27 seconds to generate the 15000 primes with the profiler attached, and only 1.43 seconds without.  One important thing I wanted to call out though was the performance graph now: Notice anything odd?  The %Processor time is above 100%.  This is because there is now more than 1 core in the operation.  A better label for the chart in my mind would have been %Core time, but to each their own. Another odd thing I noticed was that the profiler seemed to be spot on this time in my DumbPrimes class with line details in source, even with comments..  Odd. Profiling Web Applications The last thing that I wanted to cover, that means a lot to me as a web developer, is the great amount of work that Red Gate put into the profiler when profiling web applications.  In my solution, I have a simple MVC4 application setup with 1 page, a single input form, that will output prime values as my WPF app did.  Launching the profiler from Visual Studio as before, nothing is really different in the profiler window, however I did receive a UAC prompt for a Red Gate helper app to integrate with the web server without notification. After requesting 500, 1000, 2000, and 5000 primes, and looking at the profiler session, things are slightly different from before: As you can see, there are 4 spikes of activity in the processor time graph, but there is also something new in the call tree: That’s right – ANTS will actually group method calls by get/post operations, so it is easier to find out what action/page is giving the largest problems…  Pretty cool in my mind! Overview Overall, I think that Red Gate ANTS CLR Profiler has a lot to offer, however I think it also has a long ways to go.  3 Biggest Pros: Ability to easily drill down from time graph, to method calls, to source code Wide variety of counters to choose from when profiling your application Excellent integration/grouping of methods being called from web applications by request – BRILLIANT! 3 Biggest Cons: Issue regarding line details in source view Nit pick – Processor time vs. Core time Nit pick – Lack of full integration with Visual Studio Ratings Ease of Use (7/10) – I marked down here because of the problems with the line level details and the extra work that that entails, and the lack of better integration with Visual Studio. Effectiveness (10/10) – I believe that the profiler does EXACTLY what it purports to do.  Especially with its large variety of performance counters, a definite plus! Features (9/10) – Besides the real time performance monitoring, and the drill downs that I’ve shown here, ANTS also has great integration with ADO.Net, with the ability to show database queries run by your application in the profiler.  This, with the line level details, the web request grouping, reflector integration, and various options to customize your profiling session I think create a great set of features! Customer Service (10/10) – My entire experience with Red Gate personnel has been nothing but good.  their people are friendly, helpful, and happy! UI / UX (8/10) – The interface is very easy to get around, and all of the options are easy to find.  With a little bit of poking around, you’ll be optimizing Hello World in no time flat! Overall (8/10) – Overall, I am happy with the Performance Profiler and its features, as well as with the service I received when working with the Red Gate personnel.  I WOULD recommend you trying the application and seeing if it would fit into your process, BUT, remember there are still some kinks in it to hopefully be worked out. My next post will definitely be shorter (hopefully), but thank you for reading up to here, or skipping ahead!  Please, if you do try the product, drop me a message and let me know what you think!  I would love to hear any opinions you may have on the product. Code Feel free to download the code I used above – download via DropBox

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  • System crashes/lockups + compiz/cairo/gnome-panel crashing due to cached ram, please help?

    - by Kristian Thomson
    Can someone help me to troubleshoot system crashes and lockups which result in compiz/cairo dock and gnome-panel crashing? I also get no window borders after the crash and a lot of kernel memory errors. Logs are telling me that apps were killed due to not enough memory, but the system is caching like 14GB of my ram so I'm a bit stuck on what/how to stop it. I'm running Ubuntu 12.10 on a 2011 Mac Mini with 16 GB ram. Here's some of the logs that look like they could be causing trouble. I woke up this morning to find chrome/skype/cairo dock and a few others had been killed and here is what the log said. Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.959890] Out of memory: Kill process 12247 (chromium-browse) score 101 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.959893] Killed process 12247 (chromium-browse) total-vm:238948kB, anon-rss:17064kB, file-rss:20008kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.972283] Out of memory: Kill process 10976 (dropbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.972288] Killed process 10976 (dropbox) total-vm:316392kB, anon-rss:115484kB, file-rss:16504kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.975890] Out of memory: Kill process 10887 (rhythmbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9310.975895] Killed process 11515 (tray_icon_worke) total-vm:63336kB, anon-rss:15960kB, file-rss:11436kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.281535] Out of memory: Kill process 10887 (rhythmbox) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.281539] Killed process 10887 (rhythmbox) total-vm:528980kB, anon-rss:92272kB, file-rss:36520kB Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.283110] Out of memory: Kill process 10889 (skype) score 3 or sacrifice child Nov 5 04:00:45 linkandzelda-Macmini kernel: [ 9311.283113] Killed process 10889 (skype) total-vm:415056kB, anon-rss:84880kB, file-rss:22160kB I went to look deeper into things and saw that the whole time I'm having these kernel errors with out of memory and something mentioning radeon. I have a Radeon HD 6600M graphics card using the open source driver, not the proprietary one. I was wondering if perhaps using the proprietary one would solve the problem. Also, while writing this in Chrome rhythmbox and chrome just got killed while typing this, due to out of memory errors or so it reports, though I have 7 GB of free RAM at the time with 7 GB cached as well. Here is a full copy of my logs that happened in kern.log simply from when I began typing this question. http://pastebin.com/cdxxDktG Thanks in advance, Kris

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  • Calling all developers building ASP.NET applications

    - by Laila Lotfi
    We know that developers building desktop apps have to contend with memory management issues, and we’d like to learn more about the memory challenges ASP.NET developers are facing. To be more specific, we’re carrying out some exploratory research leading into the next phase of development on ANTS Memory Profiler, and our development team would love to speak to developers building ASP.NET applications. You don’t need to have ever used ANTS profiler – this will be a more general conversation about: - your current site architecture, and how you manage the memory requirements of your applications on your back-end servers and web services. - how you currently diagnose memory leaks and where you do this (production server, or during testing phase, or if you normally manage to get them all during the local development). - what specific memory problems you’ve experienced – if any. Of course, we’ll compensate you for your time with a $50 Amazon voucher (or equivalent in other currencies), and our development team’s undying gratitude. If you’d like to participate, please just drop me a line on [email protected].

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  • 1000baseT/Full Supported and Advertised but not working!

    - by user11973
    Hello, i'm using a AT3IONT-I motherboard with integrated card. If I ethtool it to 1000 full duplex it wont work! Here is sudo ethtool eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Advertised pause frame use: Symmetric Receive-only Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: internal Auto-negotiation: on MDI-X: Unknown Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) Link detected: yes here is sudo lshw -C network: *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:04:00.0 logical name: eth0 version: 03 serial: bc:ae:c5:8b:7d:33 size: 100MB/s capacity: 1GB/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list rom ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8168 driverversion=8.021.00-NAPI duplex=full ip=192.168.0.2 latency=0 link=yes multicast=yes port=twisted pair speed=100MB/s resources: irq:42 ioport:e800(size=256) memory:f8fff000-f8ffffff memory:f8ff8000-f8ffbfff memory:fbff0000-fbffffff And lspci -nn: 00:00.0 Host bridge [0600]: nVidia Corporation MCP79 Host Bridge [10de:0a82] (rev b1) 00:00.1 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0a88] (rev b1) 00:03.0 ISA bridge [0601]: nVidia Corporation MCP79 LPC Bridge [10de:0aad] (rev b3) 00:03.1 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0aa4] (rev b1) 00:03.2 SMBus [0c05]: nVidia Corporation MCP79 SMBus [10de:0aa2] (rev b1) 00:03.3 RAM memory [0500]: nVidia Corporation MCP79 Memory Controller [10de:0a89] (rev b1) 00:03.5 Co-processor [0b40]: nVidia Corporation MCP79 Co-processor [10de:0aa3] (rev b1) 00:04.0 USB Controller [0c03]: nVidia Corporation MCP79 OHCI USB 1.1 Controller [10de:0aa5] (rev b1) 00:04.1 USB Controller [0c03]: nVidia Corporation MCP79 EHCI USB 2.0 Controller [10de:0aa6] (rev b1) 00:06.0 USB Controller [0c03]: nVidia Corporation MCP79 OHCI USB 1.1 Controller [10de:0aa7] (rev b1) 00:06.1 USB Controller [0c03]: nVidia Corporation MCP79 EHCI USB 2.0 Controller [10de:0aa9] (rev b1) 00:08.0 Audio device [0403]: nVidia Corporation MCP79 High Definition Audio [10de:0ac0] (rev b1) 00:09.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Bridge [10de:0aab] (rev b1) 00:0b.0 RAID bus controller [0104]: nVidia Corporation MCP79 RAID Controller [10de:0abc] (rev b1) 00:0c.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0ac4] (rev b1) 00:10.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0aa0] (rev b1) 00:15.0 PCI bridge [0604]: nVidia Corporation MCP79 PCI Express Bridge [10de:0ac6] (rev b1) 03:00.0 VGA compatible controller [0300]: nVidia Corporation ION VGA [10de:087d] (rev b1) 04:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller [10ec:8168] (rev 03) If i use Code: sudo ethtool -s eth0 speed 1000 duplex full autoneg off then in ethtool speed is Unknown and it doesn't work; if I set it via pre-up it wont work either... Please help!! Thanks!

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  • What causes Multi-Page allocations?

    - by SQLOS Team
    Writing about changes in the Denali Memory Manager In his last post Rusi mentioned: " In previous SQL versions only the 8k allocations were limited by the ‘max server memory’ configuration option.  Allocations larger than 8k weren’t constrained." In SQL Server versions before Denali single page allocations and multi-Page allocations are handled by different components, the Single Page Allocator (which is responsible for Buffer Pool allocations and governed by 'max server memory') and the Multi-Page allocator (MPA) which handles allocations of greater than an 8K page. If there are many multi-page allocations this can affect how much memory needs to be reserved outside 'max server memory' which may in turn involve setting the -g memory_to_reserve startup parameter. We'll follow up with more generic articles on the new Memory Manager structure, but in this post I want to clarify what might cause these larger allocations. So what kinds of query result in MPA activity? I was asked this question the other day after delivering an MCM webcast on Memory Manager changes in Denali. After asking around our Dev team I was connected to one of our test leads Sangeetha who had tested the plan cache, and kindly provided this example of an MPA intensive query: A workload that has stored procedures with a large # of parameters (say > 100, > 500), and then invoked via large ad hoc batches, where each SP has different parameters will result in a plan being cached for this “exec proc” batch. This plan will result in MPA.   Exec proc_name @p1, ….@p500 Exec proc_name @p1, ….@p500 . . . Exec proc_name @p1, ….@p500 Go   Another workload would be large adhoc batches of the form: Select * from t where col1 in (1, 2, 3, ….500) Select * from t where col1 in (1, 2, 3, ….500) Select * from t where col1 in (1, 2, 3, ….500) … Go  In Denali all page allocations are handled by an "Any size page allocator" and included in 'max server memory'. The buffer pool effectively becomes a client of the any size page allocator, which in turn relies on the memory manager. - Guy Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • Booting 11.10 from USB stick on MacBook Pro 5,1 fails

    - by Helge Stenström
    I've created a bootable memory stick on a Windows computer, and tested it on an HP PC. It's made from a 64-bit image of Ubuntu 11.10, downloaded from http://www.ubuntu.com/download/ubuntu/download. When I boot from this memory stick, there is some kind of boot menu, where I can choose to run Ubuntu from the memory stick, or install. I select Run from memory stick. (the words may be wrong here, I'm taking it from memory.) From this point, the screen is black (but backlighted), and I can't do anything but turn off the computer. It gets hot, too. Has anyone been more successful than me? Are there known issues? The computer is a 15 inch MacBook Pro 5,1 (unibody, late 2008), 4 GB memory.

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  • Computer won't reboot without waiting for a while

    - by Benjamin
    I've got an unusual problem with my computer. When ever I reboot my computer it won't boot, I get a few beeps from the BIOS and nothing else, however if I wait for a few minuets the computer will boot perfectly. I tried to count the beeps and I get around 7-9 of them; the first two are noticeably closer together than the rest. [Edit: I'm now reasonably confident it's 1 long followed by 8 short beeps. That would be a display related issue: http://www.bioscentral.com/beepcodes/amibeep.htm] My BIOS is American Megatrends Inc and version P1.80, the Motherboard is an ASRock X58 Extreme (both according to dmidecode) Here's an output from LSPCI, I'm not sure what else might be useful but I can provide whatever's asked. 00:00.0 Host bridge: Intel Corporation 5520/5500/X58 I/O Hub to ESI Port (rev 13) 00:01.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 1 (rev 13) 00:03.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 3 (rev 13) 00:07.0 PCI bridge: Intel Corporation 5520/5500/X58 I/O Hub PCI Express Root Port 7 (rev 13) 00:14.0 PIC: Intel Corporation 5520/5500/X58 I/O Hub System Management Registers (rev 13) 00:14.1 PIC: Intel Corporation 5520/5500/X58 I/O Hub GPIO and Scratch Pad Registers (rev 13) 00:14.2 PIC: Intel Corporation 5520/5500/X58 I/O Hub Control Status and RAS Registers (rev 13) 00:14.3 PIC: Intel Corporation 5520/5500/X58 I/O Hub Throttle Registers (rev 13) 00:1a.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #4 00:1a.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #5 00:1a.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #6 00:1a.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #2 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller 00:1c.0 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 1 00:1c.1 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Port 2 00:1c.5 PCI bridge: Intel Corporation 82801JI (ICH10 Family) PCI Express Root Port 6 00:1d.0 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #1 00:1d.1 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #2 00:1d.2 USB controller: Intel Corporation 82801JI (ICH10 Family) USB UHCI Controller #3 00:1d.7 USB controller: Intel Corporation 82801JI (ICH10 Family) USB2 EHCI Controller #1 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90) 00:1f.0 ISA bridge: Intel Corporation 82801JIR (ICH10R) LPC Interface Controller 00:1f.2 SATA controller: Intel Corporation 82801JI (ICH10 Family) SATA AHCI Controller 00:1f.3 SMBus: Intel Corporation 82801JI (ICH10 Family) SMBus Controller 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) 02:00.0 FireWire (IEEE 1394): VIA Technologies, Inc. VT6315 Series Firewire Controller 02:00.1 IDE interface: VIA Technologies, Inc. VT6415 PATA IDE Host Controller (rev a0) 03:00.0 SATA controller: JMicron Technology Corp. JMB360 AHCI Controller (rev 02) 05:00.0 VGA compatible controller: nVidia Corporation GT200b [GeForce GTX 285] (rev a1) ff:00.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture Generic Non-Core Registers (rev 05) ff:00.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QuickPath Architecture System Address Decoder (rev 05) ff:02.0 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Link 0 (rev 05) ff:02.1 Host bridge: Intel Corporation Xeon 5500/Core i7 QPI Physical 0 (rev 05) ff:03.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller (rev 05) ff:03.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Target Address Decoder (rev 05) ff:03.4 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Test Registers (rev 05) ff:04.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Control Registers (rev 05) ff:04.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Address Registers (rev 05) ff:04.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Rank Registers (rev 05) ff:04.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 0 Thermal Control Registers (rev 05) ff:05.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Control Registers (rev 05) ff:05.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Address Registers (rev 05) ff:05.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Rank Registers (rev 05) ff:05.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 1 Thermal Control Registers (rev 05) ff:06.0 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Control Registers (rev 05) ff:06.1 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Address Registers (rev 05) ff:06.2 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Rank Registers (rev 05) ff:06.3 Host bridge: Intel Corporation Xeon 5500/Core i7 Integrated Memory Controller Channel 2 Thermal Control Registers (rev 05) Update: ok I installed lm-sensors and here's the output. coretemp-isa-0000 Adapter: ISA adapter Core 0: +58.0°C (high = +80.0°C, crit = +100.0°C) Core 1: +59.0°C (high = +80.0°C, crit = +100.0°C) Core 2: +58.0°C (high = +80.0°C, crit = +100.0°C) Core 3: +57.0°C (high = +80.0°C, crit = +100.0°C) it8720-isa-0a10 Adapter: ISA adapter in0: +0.93 V (min = +0.00 V, max = +4.08 V) in1: +0.06 V (min = +0.00 V, max = +4.08 V) in2: +3.25 V (min = +0.00 V, max = +4.08 V) +5V: +2.91 V (min = +0.00 V, max = +4.08 V) in4: +3.04 V (min = +0.00 V, max = +4.08 V) in5: +2.94 V (min = +0.00 V, max = +4.08 V) in6: +2.14 V (min = +0.00 V, max = +4.08 V) 5VSB: +2.96 V (min = +0.00 V, max = +4.08 V) Vbat: +3.28 V fan1: 1869 RPM (min = 0 RPM) fan2: 0 RPM (min = 0 RPM) fan3: 0 RPM (min = 0 RPM) fan4: 1106 RPM (min = -1 RPM) fan5: 225000 RPM (min = -1 RPM) temp1: +39.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor temp2: +56.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor temp3: +127.0°C (low = +0.0°C, high = +127.0°C) sensor = thermistor cpu0_vid: +1.650 V intrusion0: ALARM If it helps here's the summery from sensors-detect Driver `it87': * ISA bus, address 0xa10 Chip `ITE IT8720F Super IO Sensors' (confidence: 9) Driver `adt7475': * Bus `NVIDIA i2c adapter 3 at 5:00.0' Busdriver `nvidia', I2C address 0x2e Chip `Analog Devices ADT7473' (confidence: 5) Driver `coretemp': * Chip `Intel digital thermal sensor' (confidence: 9)

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  • disable intel gpu in ubuntu 12.04

    - by small_potato
    I am wondering if there is anything to disable the intel gpu on ubuntu 12.04. I want to be able to setup dual monitor using nvidia-settings. It seems the intel gpu is used for display as suggested by sudo lshw -c display the output is *-display description: VGA compatible controller product: NVIDIA Corporation vendor: NVIDIA Corporation physical id: 0 bus info: pci@0000:01:00.0 version: a1 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vga_controller bus_master cap_list rom configuration: driver=nvidia latency=0 resources: irq:16 memory:c0000000-c0ffffff memory:90000000-9fffffff memory:a0000000-a1ffffff ioport:4000(size=128) memory:a2000000-a207ffff *-display description: VGA compatible controller product: Haswell Integrated Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 06 width: 64 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:47 memory:c2000000-c23fffff memory:b0000000-bfffffff ioport:5000(size=64) I have a lenovoY410 with GT750M. It seems there is no way to turn off the intel gpu in bios either. Help please. Thanks.

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  • performing simple buffer overflow on Mac os 10.6

    - by REALFREE
    I'm trying to learn about stack base overflow and write a simple code to exploit stack. But somehow it doesn't work at all but showing only Abort trap on my machine (mac os leopard) I guess Mac os treats overflow differently, it won't allow me to overwrite memory through c code. for example, strcpy(buffer, input) // lets say char buffer[6] but input is 7 bytes on Linux machine, this code successfully overwrite next stack, but prevented on mac os (Abort trap) Anyone know how to perform a simple stack-base overflow on mac machine?

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  • Why is my Android app camera preview running out of memory on my AVD?

    - by Bryan
    I have yet to try this on an actual device, but expect similar results. Anyway, long story short, whenever I run my app on the emulator, it crashes due to an out of memory exception. My code really is essentially the same as the camera preview API demo from google, which runs perfectly fine. The only file in the app (that I created/use) is as below- package berbst.musicReader; import java.io.IOException; import android.app.Activity; import android.content.Context; import android.hardware.Camera; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; /********************************* * Music Reader v.0001 * Still VERY under construction. * @author Bryan * *********************************/ public class MusicReader extends Activity { private MainScreen main; @Override //Begin activity public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); main = new MainScreen(this); setContentView(main); } class MainScreen extends SurfaceView implements SurfaceHolder.Callback { SurfaceHolder sHolder; Camera cam; MainScreen(Context context) { super(context); //Set up SurfaceHolder sHolder = getHolder(); sHolder.addCallback(this); sHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void surfaceCreated(SurfaceHolder holder) { // Open the camera and start viewing cam = Camera.open(); try { cam.setPreviewDisplay(holder); } catch (IOException exception) { cam.release(); cam = null; } } public void surfaceDestroyed(SurfaceHolder holder) { // Kill all our crap with the surface cam.stopPreview(); cam.release(); cam = null; } public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { // Modify parameters to match size. Camera.Parameters params = cam.getParameters(); params.setPreviewSize(w, h); cam.setParameters(params); cam.startPreview(); } } }

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  • C: Proper syntax for allocating memory using pointers to pointers.

    - by ~kero-05h
    This is my first time posting here, hopefully I will not make a fool of myself. I am trying to use a function to allocate memory to a pointer, copy text to the buffer, and then change a character. I keep getting a segfault and have tried looking up the answer, my syntax is probably wrong, I could use some enlightenment. /* My objective is to pass a buffer to my Copy function, allocate room, and copy text to it. Then I want to modify the text and print it.*/ #include <stdio.h> #include <stdlib.h> #include <string.h> int Copy(char **Buffer, char *Text); int main() { char *Text = malloc(sizeof(char) * 100); char *Buffer; strncpy(Text, "1234567890\n", 100); Copy(&Buffer, Text); } int Copy(char **Buffer, char *Text) { int count; count = strlen(Text)+1; *Buffer = malloc(sizeof(char) * count); strncpy(*Buffer, Text, 5); *Buffer[2] = 'A'; /* This results in a segfault. "*Buffer[1] = 'A';" results in no differece in the output. */ printf("%s\n", *Buffer); }

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  • Nginx , Apache , Mysql , Memcache with server 4G ram. How optimize to enoigh of memory?

    - by TomSawyer
    i have 1 dedicated server with Nginx proxy for Apache. Memcache, mysql, 4G Ram. These day, my visitor on my site wasn't increased, but my server get overload always in some specified time. (9AM - 15PM) Ram in use is increased second by second to full. that's moment, my server will get overload. i have to kill all apache , mysql service and reboot it to get free memory. and it'll full again. that's the terrible circle. here is my ram in use at the moment 160(nginx) 220(apache) 512(memcache) 924(mysql) here's process number 4(nginx) 14(apache) 5(memcache) 20(mysql) and here's my my.cnf config. someone can help me to optimize it? [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql skip-locking skip-networking skip-name-resolve # enable log-slow-queries log-slow-queries = /var/log/mysql-slow-queries.log long_query_time=3 max_connections=200 wait_timeout=64 connect_timeout = 10 interactive_timeout = 25 thread_stack = 512K max_allowed_packet=16M table_cache=1500 read_buffer_size=4M join_buffer_size=4M sort_buffer_size=4M read_rnd_buffer_size = 4M max_heap_table_size=256M tmp_table_size=256M thread_cache=256 query_cache_type=1 query_cache_limit=4M query_cache_size=16M thread_concurrency=8 myisam_sort_buffer_size=128M # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 [mysqldump] quick max_allowed_packet=16M [mysql] no-auto-rehash [isamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [myisamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [mysqlhotcopy] interactive-timeout [mysql.server] user=mysql basedir=/var/lib [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid

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  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

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  • Write to memory buffer instead of file with libjpeg?

    - by Richard Knop
    I have found this function which uses libjpeg to write to a file: int write_jpeg_file( char *filename ) { struct jpeg_compress_struct cinfo; struct jpeg_error_mgr jerr; /* this is a pointer to one row of image data */ JSAMPROW row_pointer[1]; FILE *outfile = fopen( filename, "wb" ); if ( !outfile ) { printf("Error opening output jpeg file %s\n!", filename ); return -1; } cinfo.err = jpeg_std_error( &jerr ); jpeg_create_compress(&cinfo); jpeg_stdio_dest(&cinfo, outfile); /* Setting the parameters of the output file here */ cinfo.image_width = width; cinfo.image_height = height; cinfo.input_components = bytes_per_pixel; cinfo.in_color_space = color_space; /* default compression parameters, we shouldn't be worried about these */ jpeg_set_defaults( &cinfo ); /* Now do the compression .. */ jpeg_start_compress( &cinfo, TRUE ); /* like reading a file, this time write one row at a time */ while( cinfo.next_scanline < cinfo.image_height ) { row_pointer[0] = &raw_image[ cinfo.next_scanline * cinfo.image_width * cinfo.input_components]; jpeg_write_scanlines( &cinfo, row_pointer, 1 ); } /* similar to read file, clean up after we're done compressing */ jpeg_finish_compress( &cinfo ); jpeg_destroy_compress( &cinfo ); fclose( outfile ); /* success code is 1! */ return 1; } I would actually need to write the jpeg compressed image just to memory buffer, without saving it to a file, to save time. Could somebody give me an example how to do it? I have been searching the web for a while but the documentation is very rare if any and examples are also difficult to come by.

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  • How to cast C struct just another struct type if their memory size are equal?

    - by Eonil
    I have 2 matrix structs means equal data but have different form like these: // Matrix type 1. typedef float Scalar; typedef struct { Scalar e[4]; } Vector; typedef struct { Vector e[4]; } Matrix; // Matrix type 2 (you may know this if you're iPhone developer) struct CATransform3D { CGFloat m11, m12, m13, m14; CGFloat m21, m22, m23, m24; CGFloat m31, m32, m33, m34; CGFloat m41, m42, m43, m44; }; typedef struct CATransform3D CATransform3D; Their memory size are equal. So I believe there is a way to convert these types without any pointer operations or copy like this: // Implemented from external lib. CATransform3D CATransform3DMakeScale (CGFloat sx, CGFloat sy, CGFloat sz); Matrix m = (Matrix)CATransform3DMakeScale ( 1, 2, 3 ); Is this possible? Currently compiler prints an "error: conversion to non-scalar type requested" message.

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  • Ruby - Nokogiri - Parsing XML from memory and putting all same name node values into an array.

    - by r3nrut
    I have an XML I'm trying to parse from memory and get the status of each of my heart beat tests using Nokogiri. Here is the solution I have... xml = <a:HBeat> <a:ElapsedTime>3 ms</a:ElapsedTime> <a:Name>Service 1</a:Name> <a:Status>true</a:Status> </a:HBeat> <a:HBeat> <a:ElapsedTime>4 ms</a:ElapsedTime> <a:Name>Service 2</a:Name> <a:Status>true</a:Status> </a:HBeat> <a:HBeat> I have tried using both css and xpath to pull back the value for each Status and put it into an array. Code is below: doc = Nokogiri::XML.parse(xml) #service_state = doc.css("a:HBeat, a:Status", 'a' => 'http://schemas.datacontract.org/2004/07/OpenAPI.Entity').map {|node| node.children.text} service_state = doc.xpath("//*[@a:Status]", 'a' => 'http://schemas.datacontract.org/2004/07/OpenAPI.Entity').map(&:text) Both will return service_state = []. Any thoughts or recommendations? Also, consider that I have almost identical xml for another test and I used the following snippet of code which does exactly what I wanted but for some reason isn't working with the xml that contains namespaces. service_state = doc.css("HBeat Status").map(&:text) Thanks!

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  • How to draw a part of a window into a memory device context?

    - by Nell
    I'm using simple statements to keep it, er, simple: The screen goes from 0, 0 to 1000, 1000 (screen coordinates). A window goes from 100, 100 to 900, 900 (screen coordinates). I have a memory device context that goes from 0, 0 to 200, 200 (logical coordinates). I need to send a WM_PRINT message to the window. I can pass the device context to the window via WM_PRINT, but I cannot pass which part of its window it should draw into the device context. Is there some way to alter the device context that will result in the window drawing a specific part of itself into the device context (say, its bottom right portion from 700, 700 to 900, 900)? (This is all under plain old GDI and in C or C++. Any solution must be too.) Please note: This problem is part of a larger solution in which the device context size is fixed and speed is crucial, so I cannot draw the window in full into a separate device context and blit the part I want from the resultant full bitmap into my device context.

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  • Faster or more memory-efficient solution in Python for this Codejam problem.

    - by jeroen.vangoey
    I tried my hand at this Google Codejam Africa problem (the contest is already finished, I just did it to improve my programming skills). The Problem: You are hosting a party with G guests and notice that there is an odd number of guests! When planning the party you deliberately invited only couples and gave each couple a unique number C on their invitation. You would like to single out whoever came alone by asking all of the guests for their invitation numbers. The Input: The first line of input gives the number of cases, N. N test cases follow. For each test case there will be: One line containing the value G the number of guests. One line containing a space-separated list of G integers. Each integer C indicates the invitation code of a guest. Output For each test case, output one line containing "Case #x: " followed by the number C of the guest who is alone. The Limits: 1 = N = 50 0 < C = 2147483647 Small dataset 3 = G < 100 Large dataset 3 = G < 1000 Sample Input: 3 3 1 2147483647 2147483647 5 3 4 7 4 3 5 2 10 2 10 5 Sample Output: Case #1: 1 Case #2: 7 Case #3: 5 This is the solution that I came up with: with open('A-large-practice.in') as f: lines = f.readlines() with open('A-large-practice.out', 'w') as output: N = int(lines[0]) for testcase, i in enumerate(range(1,2*N,2)): G = int(lines[i]) for guest in range(G): codes = map(int, lines[i+1].split(' ')) alone = (c for c in codes if codes.count(c)==1) output.write("Case #%d: %d\n" % (testcase+1, alone.next())) It runs in 12 seconds on my machine with the large input. Now, my question is, can this solution be improved in Python to run in a shorter time or use less memory? The analysis of the problem gives some pointers on how to do this in Java and C++ but I can't translate those solutions back to Python.

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  • How to use strtok in C properly so there is no memory leak?

    - by user246392
    I am somewhat confused by what happens when you call strtok on a char pointer in C. I know that it modifies the contents of the string, so if I call strtok on a variable named 'line', its content will change. Assume I follow the bellow approach: void function myFunc(char* line) { // get a pointer to the original memory block char* garbageLine = line; // Do some work // Call strtok on 'line' multiple times until it returns NULL // Do more work free(garbageLine); } Further assume that 'line' is malloced before it is passed to myFunc. Am I supposed to free the original string after using strtok or does it do the job for us? Also, what happens if 'line' is not malloced and I attempt to use the function above? Is it safer to do the following instead? (Assume the programmer won't call free if he knows the line is not malloced) Invocation char* garbageLine = line; myFunc(line); free(garbageLine); Function definition void function myFunc(char* line) { // Do some work // Call strtok on 'line' multiple times until it returns NULL // Do more work }

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  • How does a hard drive compare to Flash memory working as a hard drive in terms of speed?

    - by Jian Lin
    Some experiment I did with hard drive read/write speed was 10MB/s write and 40MB/s read, and with a USB Flash drive, it can be 5MB/s write and 10MB/s read. Also, if I put a virtual hard drive .vhd file in a hard drive or in a USB Flash drive and try a Virtual Machine using it, the one using the hard drive is quite fast, while the one using the USB Flash drive is close to not usable. So I wonder some early netbooks use 4GB or 8GB flash memory as the hard drive, and even the Apple Mac Air has an option of using flash memory instead of a hard drive. But in those situation, will the speed be slower than using a hard drive, like in the case of a USB Flash drive?

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  • How do I make kdump use a permissible range of memory for the crash kernel?

    - by Philip Durbin
    I've read the Red Hat Knowledgebase article "How do I configure kexec/kdump on Red Hat Enterprise Linux 5?" at http://kbase.redhat.com/faq/docs/DOC-6039 and http://prefetch.net/blog/index.php/2009/07/06/using-kdump-to-get-core-files-on-fedora-and-centos-hosts/ The crashkernel=128M@16M kernel parameter works fine for me in a RHEL 6.0 beta VM, but not on the RHEL 5.5 hosts I've tried. dmesg shows me: Memory for crash kernel (0x0 to 0x0) notwithin permissible range disabling kdump Here's the line from grub.conf: kernel /vmlinuz-2.6.18-194.3.1.el5 ro root=/dev/md2 console=ttyS0,115200 panic=15 rhgb quiet crashkernel=128M@16M How do I make kdump use a permissible range of memory for the crash kernel?

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  • What solutions do I have to enforce memory limit on PHP server?

    - by Zulgrib
    I would like to enforce memory limit on a folder basis (and have it applied on subfolders) but I don't want the user able to change the memory limit. I know I can disable ini_set and I know I can enforce a hard limit or deny ini_set with Suhosin. With the first one, I doubt it will block changing it from the user.ini file, for the second, the user may still be able to change it to the hard limit I enforce with Suhosin. In both cases, I would prefer to not entierly block ini_set because it may have a legit use for other settings. In case it is important, I'm using PHP version 5.4.4 with nginx (PHP in FPM mode)

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  • how much more memcache memory do i need to get 95% hit ratio? [on hold]

    - by OneSolitaryNoob
    I have a memcache instance running that has a 90% hit ratio. How can I estimate how much more memory it needs to get to a 95% hit ratio? edit: This question was blocked, but I do not think this is impossible to answer. After all, anyone that's used a caching system HAS answered this question, most likely with trial&error&luck. I can look at my usage patterns. I can increase or decrease memory and see how hit rate changes. Both of these provide data that informs an estimate. But what's a good/better/best way to do this?

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