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• What is the fastest way to copy content of DVD to hard disc using Linux

  - by Ritesh

  I have gone through some of the links Which talks about fastest way of copying files in windows using FILE_FLAG_NO_BUFFERING and FILE_FLAG_OVERLAPPED . It also talks about how request made for read and write opeartions with BUFFER SIZE as 256KB and 128KB are faster than 1Mb .The link for that is :- Explanation for tiny reads (overlapped, buffered) outperforming large contiguous reads? I am also loking for a Similar method in linux Which allows me to copy the content of my DVD to Hard Disc in a fast Way . So I wanted to know Is there some file operation flags in Linux which would provide me the best result or Which way of Copy in Linux is the best ? My codes are all in c++.

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• PHP APC - Why is loading cached array op codes slow?

  - by Aaron Kreider

  I'm using APC to reduce my loading time for my PHP files. My files load very fast, except for one file where I define more than 100 arrays. This 270 kb file takes 200 ms to load. The rest of the files are full of objects, methods, and functions. I'm wondering: does OP code caching not work as well for arrays? My APC cache should be big enough to handle all of my classes. Currently 40% of my cache is free. My hit rate is 99%. apc.shm_size=32 M apc.max_file_size = 1M apc.shm_segments= 1 APC 3.1.6 I'm using PHP 5.2, Apache 2, and Windows Vista.

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• Effecient data structure design

  - by Sway

  Hi there, I need to match a series of user inputed words against a large dictionary of words (to ensure the entered value exists). So if the user entered: "orange" it should match an entry "orange' in the dictionary. Now the catch is that the user can also enter a wildcard or series of wildcard characters like say "or__ge" which would also match "orange" The key requirements are: * this should be as fast as possible. * use the smallest amount of memory to achieve it. If the size of the word list was small I could use a string containing all the words and use regular expressions. however given that the word list could contain potentially hundreds of thousands of enteries I'm assuming this wouldn't work. So is some sort of 'tree' be the way to go for this...? Any thoughts or suggestions on this would be totally appreciated! Thanks in advance, Matt

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• Branching logic in an MVC view

  - by Alex Kilpatrick

  I find myself writing a lot of code in my views that looks like the code below. In this case, I want to add some explanatory HTML for a novice, and different HTML for an expert user. <% if (ViewData["novice"] != null ) { % some extra HTML for a novice <% } else { % some HTML for an expert <% } % This is presentation logic, so it makes sense that it is in a view vs the controller. However, it gets ugly really fast, especially when ReSharper wants to move all the braces around to make it even uglier (is there a way to turn that off for views?). My question is whether this is proper, or should I branch in the controller to two separate views? If I do two views, I will have a lot of duplicated HTML to maintain. Or should I do two separate views with a shared partial view of the stuff that is in common?

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• gcc options for fastest code

  - by rwallace

  I'm distributing a C++ program with a makefile for the Unix version, and I'm wondering what compiler options I should use to get the fastest possible code (it falls into the category of programs that can use all the computing power they can get and still come back for more), given that I don't know in advance what hardware, operating system or gcc version the user will have, and I want above all else to make sure it at least works correctly on every major Unix-like operating system. Thus far, I have g++ -O3 -Wno-write-strings, are there any other options I should add? On Windows, the Microsoft compiler has options for things like fast calling convention and link time code generation that are worth using, are there any equivalents on gcc? (I'm assuming it will default to 64-bit on a 64-bit platform, please correct me if that's not the case.)

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• Why is doing a top(1) on an indexed column in mssql slow?

  - by reinier

  I'm puzzled by the following. I have a DB with around 10 million rows, and (among other indices) on 1 column is an index. Now I have 700k rows where the campaignid is indeed 3835 For all these rows, the connectionid is the same. I just want to find out this connectionid. use messaging_db; SELECT TOP (1) connectionid FROM outgoing_messages WITH (NOLOCK) WHERE (campaignid_int = 3835) Now this query takes approx 30 seconds to perform! I (with my small db knowledge) would expect that it would take any of the rows, and return me that connectionid If I test this same query for a campaign which only has 1 entry, it goes really fast. So the index works. How would I tackle this and why does this not work?

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• jquery change function into code for plugin

  - by jaap Klevering

  Help would be greatly appreciated. What is the correct markup that would change this function into a plugin. I tried, but cant make it to work. $(document).ready(function(){ $('ul.tabNav a').click(function() { var curChildIndex = $(this).parent().prevAll().length + 1; $(this).parent().parent().children('.current').removeClass('current'); $(this).parent().addClass('current'); $(this).parent().parent().next('.tabContainer').children('.current').slideUp('fast',function() { $(this).removeClass('current'); $(this).parent().children('div:nth-child('+curChildIndex+')').slideDown('normal',function() { $(this).addClass('current'); }); }); return true; }); });

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• How to I correctly add brackets to this code

  - by Mohammad

  This code removes whites paces, (fyi: it's credited to be very fast) function wSpaceTrim(s){ var start = -1, end = s.length; while (s.charCodeAt(--end) < 33 ); //here while (s.charCodeAt(++start) < 33 ); //here also return s.slice( start, end + 1 ); } The while loops don't have brackets, how would i correctly add brackets to this code? while(iMean){ like this; } Thank you so much!

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• How might one develop a program like FRAPS?

  - by blood

  I would like to make a program to capture video. What is the best way to capture video? I know C++ and I'm learning assembly. I found in my assembly book that I can get data from the video card. Would that be the best way? I know FRAPS hooks into programs, but I would like my program to take video of the entire screen. I would like something something fast, with low memory usage if possible. A requirement is that the program must be usable on other computers, despite dissimilar hardware.

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• Silverlight 3 ArcSegment to always draw circle's

  - by kapaboo

  Hi everyone, Ok, my arcSegment must always draw Circle's. For this reason I calculate the Arc's Width with the following formula: arcXRadius = (4 * Math.Pow(height, 2) + Math.Pow(distanceArcPoints, 2)) / (8 * height); so Arcs.Size = (arcXRadius,height) But seems that the height is scaled down when drawn. I want to add a small Circle to the Arc's middle (highest point) so when you drag it it changes the arc Height but also changes the Width so it will remain a circle. Here's how I calculate the Circle's (highest) point: Point middlePoint = GetMiddlePoint(arcPointA,arcPointB); double arcYRadius = arcSegment.Size.Height; if (arcYRadius <= 0) return middlePoint; double angle = arcSegment.RotationAngle; Point ellinewPoint = new Point(); ellinewPoint.X = Math.Cos((angle + 90) * Math.PI / 180) * arcYRadius + middlePoint.X; ellinewPoint.Y = Math.Sin((angle + 90) * Math.PI / 180) * arcYRadius + middlePoint.Y; Until Arc's.Size.Height Property gets Closer to the Width my Circle is not at the right Point. So maybe someone can give me a hint or tell me what am I doing wrong. Cheers, kapaboo

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• PHP / javascript live chat using too much bandwidth

  - by David

  So I am learning about javascript, so I am making a live chat system with PHP and javascript. I have it so the javascript refreshes the log (each message gets logged in a file on the server), and it refreshes every second. Im using firebug to monitor the resource usage, and I see under the net tab each times its updated, and the bytes add up really fast. I know I can change it to update less, but is there a way that when a user on the other end I'm talking to, when the send a message, it gets sent to the server, then an alert gets sent to me saying that the chatlog needs to update somehow. That way it only updates when the log is updated. let me know, thanks

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• problem with HttpWebRequest.GetResponse perfomance in multithread applcation

  - by Nikita

  I have very bad perfomance of HttpWebRequest.GetResponse method when it is called from different thread for different URLs. For example if we have one thread and execute url1 it requires 3sec. If we ececute url1 and url2 in parallet it requires 10sec, first request ended after 8sec and second after 10sec. If we exutet 10 URLs url1, url2, ... url0 it requires 1min 4 sec!!! first request ended after 50 secs! I use GetResponse method. I tried te set DefaultConnectionLimit but it doesn't help. If use BeginGetRequest/EndGetResponse methods it works very fast but only if this methods called from one thread. If from different it is also very slowly. I need to execute Http requests from many threads at one time. ?an anyone ever encountered such a problem? Thank you for any suggestions.

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• Applying a pixel shader effect to a portion of an image

  - by Nick

  I have a ScrollViewer that contains a very large video (16 megapixel @ 10fps) and I want to apply a pixel shader effect to it. Given the size of the images I can't apply the effect directly to the image. So I apply the effect to the ScrollContentPresenter in the control style. Which is great, everything runs nice and fast. However, I'm also rendering annotations inside of the ScrollContentPresenter which I do NOT want effects applied to (but they need to move and scale along with the image). Is there to apply the effect just to the clipped and displayed portion of the image or do I need to build a rather more complex control?

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• how to optimize an oracle query that has to_char in where clause for date

  - by panorama12

  I have a table that contains about 49403459 records. I want to query the table on a date range. say 04/10/2010 to 04/10/2010. However, the dates are stored in the table as format 10-APR-10 10.15.06.000000 AM (time stamp). As a result. When I do: SELECT bunch,of,stuff,create_date FROM myTable WHERE TO_CHAR (create_date,'MM/DD/YYYY)' >= '04/10/2010' AND TO_CHAR (create_date, 'MM/DD/YYYY' <= '04/10/2010' I get 529 rows but in 255.59 seconds! which is because I guess I am doing to_char on EACH record. However, When I do SELECT bunch,of,stuff,create_date FROM myTable WHERE create_date >= to_date('04/10/2010','MM/DD/YYYY') AND create_date <= to_date('04/10/2010','MM/DD/YYYY') then I get 0 results in 0.14 seconds. How can I make this query fast and still get valid (529) results?? At this point I can not change indexes. Right now I think index is created on create_date column

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• Can this loop be sped up in pure Python?

  - by Noctis Skytower

  I was trying out an experiment with Python, trying to find out how many times it could add one to an integer in one minute's time. Assuming two computers are the same except for the speed of the CPUs, this should give an estimate of how fast some CPU operations may take for the computer in question. The code below is an example of a test designed to fulfill the requirements given above. This version is about 20% faster than the first attempt and 150% faster than the third attempt. Can anyone make any suggestions as to how to get the most additions in a minute's time span? Higher numbers are desireable. EDIT: This experiment is being written in Python 3.1 and is 15% faster than the fourth speed-up attempt. def start(seconds): import time, _thread def stop(seconds, signal): time.sleep(seconds) signal.pop() total, signal = 0, [None] _thread.start_new_thread(stop, (seconds, signal)) while signal: total += 1 return total if __name__ == '__main__': print('Testing the CPU speed ...') print('Relative speed:', start(60))

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• Implications of Fulltext Search over many columns

  - by Alex

  Hello, I have a really wide table which includes separate columns for billing address, shipping address, primary address, names, aliases etc. (I can't normalize this table further, and that's not the question here anyways). I'm implementing SQL Server fulltext search, and I'm wondering whether I should limit the search ability to just the primary fields (primary address and names for example), or if I can extend the search ability across all columns without occurring too much of a performance or memory penalty. I've done some basic testing with 10,000 sample rows and it's quite fast but I don't have much experience with fulltext indexing, especially its dictionary internals, so I don't know if the index is going to grow over time, or if there is anything else to consider. Thoughts?

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• packing fields of a class into a byte array in c#

  - by alex

  Hi all: I am trying to create a fast way to convert c# classes into byte array. I thought of serializing the class directly to a byte array using an example I found: // Convert an object to a byte array private byte[] ObjectToByteArray(Object obj) { if(obj == null) return null; BinaryFormatter bf = new BinaryFormatter(); MemoryStream ms = new MemoryStream(); bf.Serialize(ms, obj); return ms.ToArray(); } But the byte array I got contains some other information that are not related to the fields in the class. I guess it is also converting the Properties of the class. Is there a way to serialize only the fields of the class to a byte array? Thanks

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• how to make a program like fraps.

  - by blood

  i want to make a program that will capture video. what if the best way to captrue the video, i know c++ and im learning assembly and i found in my assembly book i can get data from the video card i think? would that be the best way? i know fraps hooks into programs but i want my program to take the full screen? so i want something fast low memory useage if i can and something i can use on other computers with them having the same hardware.

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• Need help on nested loop of queries in php and mysql?

  - by mysqllearner

  Hi, I am trying to get do this: <?php $good_customer = 0; $q = mysql_query("SELECT user FROM users WHERE activated = '1'"); // this gives me about 40k users while($r = mysql_fetch_assoc($q)){ $money_spent = 0; $user = $r['user']; // Do queries on another 20 tables for($i = 1; $i<=20 ; $i++){ $tbl_name = 'data' . $i; $q2 = mysql_query("SELECT money_spent FROM $tbl_name WHERE user = '{$user}'"); while($r2 = mysql_fetch_assoc($q2)){ $money_spend += $r2['money_spent']; } if($money_spend > 1000000){ $good_customer += 1; } } } This is just an example. I am testing on localhost, for single user, it returns very fast. But when I try 1000, it takes forever, not even mentioned 40k users. Anyway to optimise/improve this code? EDIT: By the way, each of the others 20 tables has ~20 - 40k records

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• finding common prefix of array of strings

  - by bumperbox

  I have an array like this $sports = array( 'Softball - Counties', 'Softball - Eastern', 'Softball - North Harbour', 'Softball - South', 'Softball - Western' ); and i would like to find the longest common part of the string so in this instance, it would be 'Softball - '; I am thinking that I would follow the this process $i = 1; // loop to the length of the first string while ($i < strlen($sports[0]) { // grab the left most part up to i in length $match = substr($sports[0], 0, $i); // loop through all the values in array, and compare if they match foreach ($sports as $sport) { if ($match != substr($sport, 0, $i) { // didn't match, return the part that did match return substr($sport, 0, $i-1); } } // foreach // increase string length $i++; } // while // if you got to here, then all of them must be identical Questions is there a built in function or much simpler way of doing this ? for my 5 line array that is probably fine, but if i were to do several thousand line arrays, there would be a lot of overhead, so i would have to be move calculated with my starting values of $i, eg $i = halfway of string, if it fails, then $i/2 until it works, then increment $i by 1 until we succeed. so that we are doing the least number of comparisons to get a result If there a formula/algorithm out already out there for this kind of problem ? thanks alex

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• Silverlight 4 application on localhost runs extremely slow

  - by rams

  Silverlight 4 app running in IE8 and hosted on VS2010 internal webserver. The website takes atleast a minute to download the xap and code runs slow on client (IE8). I am running the app in debug mode and have turned intellitrace off. Symbol loading is also turned off. However if I kill the VS webserver, clean the solution, the app runs fast. 3 debugging sessions later, the app slows to a crawl. Have also tried turning off McAfee live scanning but no use. Looked in event log for any clue but found none. What could be the cause of the slowness? TIA rams

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• imported vm gives "failed to open/create network" error

  - by Colleen

  steps: 1. created a vm in windows 2. partitioned drive and installed ubuntu 3. exported the vm I created 4. mounted windows drive in ubuntu 5. imported the vm from the export, in the mounted drive 6. tried to start vm, got the following error: "Failed to open a session for the virtual machine XXXX. Failed to open/create the internal network 'HostInterfaceNetworking-Intel(R) 82579LM Gigabit Network Connection' (you might need to modprobe vboxnetflt to make it accessible) (VERR_INTNET_FLT_IF_NOT_FOUND). Result Code: NS_ERROR_FAILURE (0x80004005) Component: Console Interface: IConsole {1968b7d3-e3bf-4ceb-99e0-cb7c913317bb} " Network settings: Adapter 1: PCnet-FAST III (Bridged adapter, Intel(R) 82579LM Gigabit Network Connection)

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• What are some good ways to do intermachine locking?

  - by mike

  Our server cluster consists of 20 machines, each with 10 pids of 5 threads. We'd like some way to prevent any two threads, in any pid, on any machine, from modifying the same object at the same time. Our code's written in Python and runs on Linux, if that helps narrow things down. Also, it's a pretty rare case that two such threads want to do this, so we'd prefer something that optimizes the "only one thread needs this object" case to be really fast, even if it means that the "one thread has locked this object and another one needs it" case isn't great. What are some of the best practices?

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• which layout engine for finding coordinates of html elements on the web page?

  - by Mexx

  I am doing some web data classification task and was thinking if I could get the co-ordinates of html elements as they would appear on a web-browser without taking into consideration any css or javascript being referred in the web page. My language of programming is c++ and the need results for a couple million of pages, so it has to be fast. I know there is a Microsoft COM component which renders the page in a web browser control and then can be queried for position of different html tags. But this is not suitable in my case as it first renders the whole page which takes up a lot of time. So as I found out, there are open-source layout engines WebKit, Gecko that can probably be used for this. But that's a huge piece of code and I need someone to direct me to the right classes or right modules to look into or any previous/similar work someone has done previously. Also, please let me know what you guys think is a good choice if I want to customize the existing code for use with multiple threads to make it faster. Thanks

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• Is it possible to generate plain-old XML using Haml?

  - by lsdr

  I've been working on a piece of software where I need to generate a custom XML file to send back to a client application. The current solutions on Ruby/Rails world for generating XML files are slow, at best. Using builder or event Nokogiri, while have a nice syntax and are maintainable solutions, they consume too much time and processing. I definetly could go to ERB, which provides a good speed at the expense of building the whole XML by hand. HAML is a great tool, have a nice and straight-forward syntax and is fairly fast. But I'm struggling to build pure XML files using it. Which makes me wonder, is it possible at all? Does any one have some pointers to some code or docs showing how to do this, build a full, valid XML from HAML?

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