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• How come my Intel 520 180GB SSD performs extremely poorly?

  - by Willem

  I recently installed a new Intel 520 series 180GB SSD in my brand new MacBook Pro. The system is as follows: Model: MacBook Pro 15-inch, Late 2011 (MacBookPro8,2) Processor: 2.4 GHz Intel Core i7 Memory: 16 GB 1333 MHz DDR3 Graphics: AMD Radeon HD 6770M 1024 MB Software: Mac OS X Lion 10.7.3 Main Drive Bay: Intel 520-series 180GB SATA-3 (6GB/s negotiated link) SSD (Firmware: 400i) [80GB free] Optical Bay: Toshiba 5400 RPM 750GB SATA-2 HDD Trim: Enabled (according to Trim Enabler App) And here are the speeds I'm getting: Read: 412 MB/s Write: 186 MB/s What have I done wrong? Results expected: Read/write both 500MB/s I have seen benchmarks with lesser SSD:s (SATA-2 even) outperform my write-speeds by far. Also, Intel 520 SSD:s are supposed to be the top class of SSD:s. Trim Enabler report: This looks a bit odd compared to screenshots from their site: These is the defined S.M.A.R.T attributes (taken from Intel): And here are my S.M.A.R.T attributes read using smartctl tool from smartmontools: They don't seem very compatible. I'm going to try and look for a S.M.A.R.T attributes reader tool for OS X which might support Intel 520 series.

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• Hardware profiling [closed]

  - by mgroves

  I'd like to upgrade my computer so that it's faster when editing/rendering video. I'm thinking of first getting a faster hard drive, but I'd like to be able to run some sort of profiling software to tell me what the bottleneck is when rendering video. Any suggestions about software that can do this for preferably Windows XP and preferably for free?

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• Code Smell: Inheritance Abuse

  - by dsimcha

  It's been generally accepted in the OO community that one should "favor composition over inheritance". On the other hand, inheritance does provide both polymorphism and a straightforward, terse way of delegating everything to a base class unless explicitly overridden and is therefore extremely convenient and useful. Delegation can often (though not always) be verbose and brittle. The most obvious and IMHO surest sign of inheritance abuse is violation of the Liskov Substitution Principle. What are some other signs that inheritance is The Wrong Tool for the Job even if it seems convenient?

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• Computer experiencing slowdowns and lockups despite low cpu useage

  - by user157145

  my setup i5-2300 nvidia gtx 550 ti 6 gigs ram 600 w ocz modular psu recently reformatted and already experiencing drastic slowdown as soon as windows comes up, including repeated lockups with multiple various programs reporting that they are not responsive, then recovering after 10-30 seconds. ive checked memory and hard drive both of which come out fine. despite my plethura of worthless antiviral software im forced to assume that my illicit downloading practices have lead me into some comp trouble that i cant seem to determine. i have used ccleaner, search and destroy and malware bytes, all of which have found nothing to indicate what is causing this massive slowdown. in addition according to my resource manager my computer is operating at a load of only 30-50 percent CPU useage and 60 ram useage but taking 5-10 seconds to load files and open folders, and repeated lockups of multiple programs, especially firefox which seems to go unresponsive every 2-3 minutes. any help would be appreciated, i used a program called OTL by old timer, but cant make any sense of the results i was given. any help or suggestions would be appreciated, thank you for taking the time to read this i have avast but it didnt even find anything when i had it do a full system scan, so im thinking its clueless(also nortons, avg, and ad-aware). i also have mse but it has yet to complete a full scan it takes so long (i left it on last night but when i woke up my computer had a problem and had to restart). my hard drive has 300 gigs out of 1tb open and i already used hd tune pro, which said my harddrive was fine and its not a ssd. also im a noob at comps and only have the hd that is currently inside the computer in addition im not sure if studdering is the issue im suffering. my problem is that during my typing of these responses firefox has gone "not responsive" at least 5 times, each for times of about 5-10 seconds. when i try to control alt delete to bring up windows task manager it took 20 seconds. essentially its that my computer goes super slow at bringing up anything, or taking any action whatsoever that opens a program or file and has repeated incidents where i cant even click on whatever im trying to do because it locks up. the confusing thing about these incidents is that its right after restarting where there are minimal programs running and the computer and memory load is light.

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• Web Service gets unavailable after several concurrent calls

  - by Roman

  We are testing GoDaddy Virtual Data Center and came to a very strange issue when our web site gets unavailable. GoDaddy Support keeps saying the issue is in our web server settings, but looking at the result of our tests I doubt it. TEST ENVIRONMENT Virtual DataCenter with Windows hosted at GoDaddy.com. All servers have Windows Server 2008 R2 Datacenter, IIS 7. Server One with IP address 10.1.0.4 Server Two with IP address 10.1.0.3 Both servers are in private network not visible from outside. Port Forward with IP address 50.62.13.174. Port Forward is assigned to Server One TEST DESCRIPTION JMeter is used as a Client App to simulate 30 concurrent users sending 100 SOAP requests each. Interval between requests is 1 second. Http link used for testing: http://50.62.13.174/v2/webservices.asmx TEST ONE Test is run from a computer in our office. After JMeter starts running test, almost immediately, the link above becomes unavailable in a browser. After test completion, the link is not available in a browser for about 5 more minutes. Remote Desktop is working well, so we can connect to Server One remotely. After about 5 minutes since test completion, the link becomes available in a browser again. TEST TWO Test is run from Server Two (that is part of our virtual data center). Test works very well, no visible delays in processing. The link is available in a browser all the time. TEST THREE Test is run from Server One using localhost. The result is the same as in TEST TWO - no issues. TEST FOUR We repeated TEST ONE from other computers that we have located in different countries, all with the same result as TEST ONE. CONCLUSION As the test works well from Server Two, but does not work from outside our virtual data center, we feel there are issues with the network or its capacity. The whole behaviour looks like out requests from outside get stuck somewhere before reaching our virtual data center. Has anybody had similar issues in the past? Are there chances that something is wrong with our server settings?

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• How passively monitor for tcp packet loss? (Linux)

  - by nonot1

  How can I passively monitor the packet loss on TCP connections to/from my machine? Basically, I'd like a tool that sits in the background and watches TCP ack/nak/re-transmits to generate a report on which peer IP addresses "seem" to be experiencing heavy loss. Most questions like this that I find of SF suggest using tools like iperf. But, I need to monitor connections to/from a real application on my machine. Is this data just sitting there in the Linux TCP stack?

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• API Design Techniques

  - by Dehumanizer

  Is it right or more beautiful to name the functions with an prefix, like in Qt? Or using "many" namespaces, but 'normal' names for functions? For example, slOpenFile(); //"sl" means "some lib" vs some_lib::file_functions::openFile(); UPD: I've read somewhere that the first variant(using some prefix) is better, because the API users can perform 'fast' search among the documentation and in the Internet. E.g. by typing the magic prefix search engine starts to advice the exact functions. Is it enough to use the first variant?

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• Which network management system (NMS) to choose?

  - by QrystaL

  I need to integrate NMS in large enterprise system for data collection purposes. Primary requirements: collection by SNMP great scalability (up to 1,000 devices with 1,000 interfaces each) failover data storage in Oracle DBMS integration API (configuration, data access) Any ideas would be appreciated...

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• Number of Weeks between 2 Dates in SQL Server and Oracle

  This post gives you queries in Oracle and SQL Server to find number of weeks between 2 given dates Microsoft SQL Server Syntax: SELECT DATEDIFF (ww, '01/01/1753', '12/31/9999'); Oracle Syntax: SELECT floor(              (to_date('12/31/9999','mm/dd/yyyy')               - to_date('01/01/1753','mm/dd/yyyy')              )              / 7) diff FROM DUAL; span.fullpost {display:none;}

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• Which is faster for read access on EC2; local drive or EBS?

  - by Phillip Oldham

  Which is faster for read access on an EC2 instance; the "local" drive or an attached EBS volume? I have some data that needs to be persisted so have placed this on an EBS volume. I'm using OpenSolaris, so this volume has been attached as a ZFS pool. However, I have a large chunk of EC2 disk space that's going to go unused, so I'm considering re-purposing this as a ZFS cache volume but I don't want to do this if the disk access is going to be slower than that of the EBS volume as it would potentially have a detrimental effect.

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• Business layer access to the data layer

  - by rerun

  I have a Business layer (BL) and a Data layer (DL). I have an object o with a child objects collection of Type C. I would like to provide a semantics like the following o.Children.Add("info"). In the BL I would like to have a static CLASS that all of business layer classes uses to get a reference to the current datalayer instance. Is there any issue with that or must I use the factory pattern to limit creation to A class in the BL that knows the DL instance.

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• Include all php files in one file and include that file in every page if we're using hiphop?

  - by Hasan Khan

  I understand that in normal php if we're including a file we're merging the source of it in the script and it would take longer for that page to be parsed/processed but if we're using HipHop shouldn't it be ok to just create one single php file and include every file in it (that contains some class) and every page which needs those classes (in separate file each) can just include one single php file? Would this be ok in presence of HipHop?

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• Statistical Software Quality Control References

  - by Xodarap

  I'm looking for references about hypothesis testing in software management. For example, we might wonder whether "crunch time" leads to an increase in defect rate - this is a surprisingly difficult thing to do. There are many questions on how to measure quality - this isn't what I'm asking. And there are books like Kan which discuss various quality metrics and their utilities. I'm not asking this either. I want to know how one applies these metrics to make decisions. E.g. suppose we decide to go with critical errors / KLOC. One of the problems we'll have to deal with with that this is not a normally distributed data set (almost all patches have zero critical errors). And further, it's not clear that we really want to examine the difference in means. So what should our alternative hypothesis be? (Note: Based on previous questions, my guess is that I'll get a lot of answers telling me that this is a bad idea. That's fine, but I'd request that it's based on published data, instead of your own experience.)

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• Testing for disk write

  - by Montecristo

  I'm writing an application for storing lots of images (size <5MB) on an ext3 filesystem, this is what I have for now. After some searching here on serverfault I have decided for a structure of directories like this: 000/000/000000001.jpg ... 236/519/236519107.jpg This structure will allow me to save up to 1'000'000'000 images as I'll store a max of 1'000 images in each leaf. I've created it, from a theoretical point of view seems ok to me (though I've no experience on this), but I want to find out what will happen when there will be directories full of files in there. A question about creating this structure: is it better to create it all in one go (takes approx 50 minutes on my pc) or should I create directories as they are needed? From a developer point of view I think the first option is better (no extra waiting time for the user), but from a sysadmin point of view, is this ok? I've thought I could do as if the filesystem is already under the running application, I'll make a script that will save images as fast as it can, monitoring things as follows: how much time does it take for an image to be saved when there is no or little space used? how does this change when the space starts to be used up? how much time does it take for an image to be read from a random leaf? Does this change a lot when there are lots of files? Does launching this command sync; echo 3 | sudo tee /proc/sys/vm/drop_caches has any sense at all? Is this the only thing I have to do to have a clean start if I want to start over again with my tests? Do you have any suggestions or corrections?

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• High Load - Low IO - Low CPU usage

  - by devup

  I have a system whose load is rather high. As you can see from the top output below, CPU usage and I/O is negligible: top - 17:31:59 up 4 days, 2:34, 2 users, load average: 1.00, 0.99, 1.00 Tasks: 71 total, 1 running, 70 sleeping, 0 stopped, 0 zombie Cpu(s): 2.0%us, 2.0%sy, 0.0%ni, 95.9%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 960720k total, 707288k used, 253432k free, 67328k buffers Swap: 2811896k total, 2644k used, 2809252k free, 528928k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 15310 root 20 0 2512 1128 888 R 2.1 0.1 0:00.05 top I would appreciate any assistance with isolating the cause(s) of high load for when I/O and CPU are not factors.

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• Validating data to nest if or not within try and catch

  - by Skippy

  I am validating data, in this case I want one of three ints. I am asking this question, as it is the fundamental principle I'm interested in. This is a basic example, but I am developing best practices now, so when things become more complicated later, I am better equipped to manage them. Is it preferable to have the try and catch followed by the condition: public static int getProcType() { try { procType = getIntInput("Enter procedure type -\n" + " 1 for Exploratory,\n" + " 2 for Reconstructive, \n" + "3 for Follow up: \n"); } catch (NumberFormatException ex) { System.out.println("Error! Enter a valid option!"); getProcType(); } if (procType == 1 || procType == 2 || procType == 3) { hrlyRate = hrlyRate(procType); procedure = procedure(procType); } else { System.out.println("Error! Enter a valid option!"); getProcType(); } return procType; } Or is it better to put the if within the try and catch? public static int getProcType() { try { procType = getIntInput("Enter procedure type -\n" + " 1 for Exploratory,\n" + " 2 for Reconstructive, \n" + "3 for Follow up: \n"); if (procType == 1 || procType == 2 || procType == 3) { hrlyRate = hrlyRate(procType); procedure = procedure(procType); } else { System.out.println("Error! Enter a valid option!"); getProcType(); } } catch (NumberFormatException ex) { System.out.println("Error! Enter a valid option!"); getProcType(); } return procType; } I am thinking the if within the try, may be quicker, but also may be clumsy. Which would be better, as my programming becomes more advanced?

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• How do you name your personal libraries?

  - by Mehrdad

  I'm pretty bad with naming things. The only name I can every generically come up with is 'helper'. Say, if I have a header file that contains helping functions for manipulating paths, I tend to put it inside my "helper" directory and call it "path-helper.hpp" or something like that. Obviouslly, that's a bad naming convention. :) I want to have a consistent naming scheme for my folder (and namespace) which I can use to always refer to my own headers and libraries, but I have trouble finding names that are easy to type or remember (like boost)... so I end up calling some of them "helper" or "stdext" or whatnot, which isn't a great idea. How do you find names for your libraries that are easy to remember and easy to type, and which aren't too generic (like "helper" or "std" or "stdext" or the like)? Any suggestions on how to go about doing this?

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• One Does Like To Code: DevoxxUK

  - by Tori Wieldt

  What's happening at Devoxx UK? I'll be talking to Rock Star speakers, Community leaders, authors, JSR leads and more.  This video is a short introduction.   Check out these great sessions: Thursday, June 12Perchance to Stream with Java 8by Paul Sandoz13:40 - 14:30 | Room 1 Making the Internet-of-Things a Reality with Embedded Javaby Simon Ritter11:50 - 12:40 | Room 4 Java SE 8 Lambdas and Streams Labby Simon Ritter17:00 - 20:00 | Room Mezzanine Safety Not Guaranteed: Sun. Misc. Unsafe and the Quest for Safe Alternativesby Paul Sandoz18:45 - 19:45 | Room 3 Join the Java EvolutionHeather VanCuraPatrick Curran19:45 – 20:45 | Room 2  Glassfish is Here to StayDavid DelabasseeAntonio Goncalves19:45 – 20:45 | Room Expo Here is the full line-up of sessions. Devoxx UK includes a Hackergarten, where can devs work an Open Source project of their choice. The Adopt OpenJDK and Adopt a JSR Program folks will be there to help attendees contribute back to Java SE and Java EE itself!   Saturday includes a special Devoxx4Kids event in conjunction with the London Java Community. It's design to teach 10-16 year-olds simple programming concepts, robotics, electronics, and games making. Workshops include LEGO Mindstorms (robotic engineering), Greenfoot (programming), Arduino (electronics), Scratch (games making), Minecraft Modding (game hacking) and NAO (robotic programming). Small fee, you must register. If you can't attend Devoxx UK in person, stay tuned to the YouTube/Java channel. I'll be doing plenty of interviews so you can join the fun from around the world. 

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• Is it good to review programs with seniors and boss even if it is working fine?

  - by Himanshu

  In my company, before delivery of any project, my boss asks my seniors to review programs written by me or other team members or sometimes boss also sits with us for review. I think it is a good way of getting knowledge, but sometimes when programs are working fine, they don't work same after review and I need to look again into my program. They says that review helps to optimize program and query execution, but can we prefer optimization over actual functioning of program?

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• An adequate message authentication code for REST

  - by Andras Zoltan

  My REST service currently uses SCRAM authentication to issue tokens for callers and users. We have the ability to revoke caller privileges and ban IPs, as well as impose quotas to any type of request. One thing that I haven't implemented, however, is MAC for requests. As I've thought about it more, for some requests I think this is needed, because otherwise tokens can be stolen and before we identify this and deactivate the associated caller account, some damage could be done to our user accounts. In many systems the MAC is generated from the body or query string of the request, however this is difficult to implement as I'm using the ASP.Net Web API and don't want to read the body twice. Equally importantly I want to keep it simple for callers to access the service. So what I'm thinking is to have a MAC calculated on: the url, possibly minus query string the verb the request ip (potentially is a barrier on some mobile devices though) utc date and time when the client issues the request. For the last one I would have the client send that string in a request header, of course - and I can use it to decide whether the request is 'fresh' enough. My thinking is that whilst this doesn't prevent message body tampering it does prevent using a model request to use as a template for different requests later on by a malicious third party. I believe only the most aggressive man in the middle attack would be able to subvert this, and I don't think our services offer any information or ability that is valuable enough to warrant that. The services will use SSL as well, for sensitive stuff. And if I do this, then I'll be using HMAC-SHA-256 and issuing private keys for HMAC appropriately. Does this sound enough? Have I missed anything? I don't think I'm a beginner when it comes to security, but when working on it I always. am shrouded in doubt, so I appreciate having this community to call upon!

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• Bad idea to keep htop running?

  - by Michael T. Smith

  I'm now monitoring multiple servers (3) and in the coming weeks that'll increase (towards 5 or 6). I've been keeping three terminal windows open running htop via SSH and I'm now wondering if there are any downsides to having a connection constantly open to production servers?

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• Paid Website Code Review

  - by clifgray

  I have written a pretty extensive webapp and it is going to go live in the next fews weeks and before I really publicize it I want to get some professionals to review it for optimization and best practices. Is there any online service or way to find local software engineers who would be willing to do this? Just to give some specifics that may be helpful, my site is on Google App Engine and written in Python and it is tough to find someone with extensive experience in that area.

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• Enabling DMA in pc with windows 7

  - by Mugen

  I was checking my pc settings using AIDA64 (supposed to be the successor for Everest - it basically shows you detailed hardware you currently have). For my ATA hard disk it shows the setting for DMA as "supported, disabled". But when I checked the windows setting I see that it is actually enabled. How can I find out which is correct? And if its disabled what do I do to enable it? Thanks for your help. Here are some screenshots for this:

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• Can somebody help me setting up wxWidgets 3.0 for codeblocks12.11 on ubuntu 12.04?

  - by NewGuy

  I already downloaded and installed codeblocks 12.11svn9156. After that, I downloaded and compiled wxWidgets3.0 using make. When I go to codeblocks I don't see wxWidgets3.0 in the wxWidget project wizard. Also, the wizard prompts me "wxSmith plugin is not loaded, can not continue" I know some additional steps have to be done but I only found some confusing documentation. Thank you very much in advance.

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• Creating collection with no code (almost)

  - by Sean Feldman

  When doing testing, I tend to create an object mother for the items generated multiple times for specifications. Quite often these objects need to be a part of a collection. A neat way to do so is to leverage .NET params mechanism: public static IEnumerable<T> CreateCollection<T>(params T[] items) { return items; } And usage is the following: private static IEnumerable<IPAddress> addresses = CreateCollection(new IPAddress(123456789), new IPAddress(987654321));

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