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  • Measuring execution time of selected loops

    - by user95281
    I want to measure the running times of selected loops in a C program so as to see what percentage of the total time for executing the program (on linux) is spent in these loops. I should be able to specify the loops for which the performance should be measured. I have tried out several tools (vtune, hpctoolkit, oprofile) in the last few days and none of them seem to do this. They all find the performance bottlenecks and just show the time for those. Thats because these tools only store the time taken that is above a threshold (~1ms). So if one loop takes lesser time than that then its execution time won't be reported. The basic block counting feature of gprof depends on a feature in older compilers thats not supported now. I could manually write a simple timer using gettimeofday or something like that but for some cases it won't give accurate results. For ex: for (i = 0; i < 1000; ++i) { for (j = 0; j < N; ++j) { //do some work here } } Now here I want to measure the total time spent in the inner loop and I will have to put a call to gettimeofday inside the first loop. So gettimeofday itself will get called a 1000 times which introduces its own overhead and the result will be inaccurate.

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  • Java Performance measurement

    - by portoalet
    Hi, I am doing some Java performance comparison between my classes, and wondering if there is some sort of Java Performance Framework to make writing performance measurement code easier? I.e, what I am doing now is trying to measure what effect does it have having a method as "synchronized" as in PseudoRandomUsingSynch.nextInt() compared to using an AtomicInteger as my "synchronizer". So I am trying to measure how long it takes to generate random integers using 3 threads accessing a synchronized method looping for say 10000 times. I am sure there is a much better way doing this. Can you please enlighten me? :) public static void main( String [] args ) throws InterruptedException, ExecutionException { PseudoRandomUsingSynch rand1 = new PseudoRandomUsingSynch((int)System.currentTimeMillis()); int n = 3; ExecutorService execService = Executors.newFixedThreadPool(n); long timeBefore = System.currentTimeMillis(); for(int idx=0; idx<100000; ++idx) { Future<Integer> future = execService.submit(rand1); Future<Integer> future1 = execService.submit(rand1); Future<Integer> future2 = execService.submit(rand1); int random1 = future.get(); int random2 = future1.get(); int random3 = future2.get(); } long timeAfter = System.currentTimeMillis(); long elapsed = timeAfter - timeBefore; out.println("elapsed:" + elapsed); } the class public class PseudoRandomUsingSynch implements Callable<Integer> { private int seed; public PseudoRandomUsingSynch(int s) { seed = s; } public synchronized int nextInt(int n) { byte [] s = DonsUtil.intToByteArray(seed); SecureRandom secureRandom = new SecureRandom(s); return ( secureRandom.nextInt() % n ); } @Override public Integer call() throws Exception { return nextInt((int)System.currentTimeMillis()); } } Regards

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  • How do I populate these fields from existing data?

    - by dmanexe
    I'm not sure how to make a few parts of my form to populate from data from an array I'm passing from the database. First is this <select> object. The key estimate_lead_id in the database holds the value, and I want the dropdown to auto-select based on the value from the database. <select name="estimate_lead_id"> <? foreach($leads->result() as $lead) { ?> <option value="<?=$lead->id?>"><?=$lead->lead_name?></option> <? } ?> </select> Second (this is a little more complex), I have created a script that loops through and gets all of the items from each respective category. What I can't get it to do though is loop through these items and only display the items in the estimate, and then fill the fields with the respective values from the database. <?php foreach ($items['items_poolconcretedecking']->result() as $item) { ?> <input type="checkbox" name="measure[<?=$item->id?>][checkmark]" value="<?=$item->id?>"> <input class="item_mult" value="" type="text" name="measure[<?=$item->id?>][quantity]" /> <?php } ?>

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  • Automatic music rating based on listening habits

    - by marco92w
    I've created a Winamp-like music player in Delphi. Not so complex, of course. Just a simple one. But now I would like to add a more complex feature: Songs in the library should be automatically rated based on the user's listening habits. This means: The application should "understand" if the user likes a song or not. And not only whether he/she likes it but also how much. My approach so far (data which could be used): Simply measure how often a song was played per time. Start counting time when the song was added to the library so that recent songs don't have any disadvantage. Measure how long a song was played on average (minutes). Starting a song but directly change to another one should have a bad influence on the ranking since the user didn't seem to like the song. ... Could you please help me with this problem? I would just like to have some ideas. I don't need the implementation in Delphi.

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  • iPhone: How to Determine Average Light/Dark of an Area of an UIImage

    - by TechZen
    I need to place labels with a transparent background over a variable-content UIImage. Readability will vary significantly depending on the relationship between the color of the label's text and the color/luminosity of the area of the image displayed under the label. Since the image will be constantly changing, the color of the label's text needs to change in sync. I have found several techniques for determining the color, perceived luminosity etc of a single pixel. However, I need to rather quickly (while a view loads) determine the rough perceived color/luminosity of an area of the UIImage under the frame of the UILabel. I presume I will also need to measure the alpha because the same color/luminosity looks different at different alpha values. Is there a way to calculate such a value for an area? Will I be reduced to simply summing pixels? If it comes to that, is there an algorithm to accomplish this? I've thought of two possible approaches: Perform some "folding" operations i.e. combining pixels from one half of the area to the other half. Then repeat until I get a single value. Would this be practical? How would you logically combine pixels to average their perceived color/luminosity? Sample a statistically significant number of pixels in the area and then combine them (somehow) to get a rough measure. I think this problem comes up a lot these days with people being so found of customizing backgrounds. Seems like something that would be worth my time to bang out a category or class to handle this and then share it around.

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  • How to stop input in Perl?

    - by user1472747
    First time poster and part time perl noobie. I'm making a reflex game. Here's the output - __________________________________________________________________________ Reflex game initiated. Press ENTER to begin the game, and then press ENTER after the asterisks are printed to measure your reflexes!. ************************* Your result: 0.285606 seconds. logout [Process completed] __________________________________________________________________________ There's one small problem though - There's 0-10 seconds (based on a random variable) after you press enter to start the game and before the stars are printed. During that time, if the player presses ENTER, it's logged as their reflex time. So I need a way to stop my code from reading their ENTER button before the stars are printed. The code - #!/usr/bin/perl use Time::HiRes qw(sleep); use Time::HiRes qw(gettimeofday); #random delay variable $random_number = rand(); print "Reflex game initiated. Press ENTER to begin the game, and then press ENTER after the asterisks are printed to measure your reflexes!.\n"; #begin button $begin = <>; #waits x milliseconds sleep(10*$random_number); #pre-game $start = [ Time::HiRes::gettimeofday() ]; print "\n****************************\n"; #user presses enter $stop = <>; #post game $elapsed = Time::HiRes::tv_interval($start); #delay time print print "Your result: ".$elapsed." seconds.\n";

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  • why does setting stderr=subprocess.STDOUT fix a subprocess.check_output call?

    - by ShankarG
    I have a python script running on a small server that is called in three different ways - from within another python script, by cron, or by gammu-smsd (an SMS daemon with the wonderful mobile utility [gammu]). The script is for maintenance and contained the following kludge to measure used space on the system (presumably this is possible from within Python, but this was quick and dirty): reportdict['Used Space'] = subprocess.check_output(["df / | tail -1 | awk '{ print $5; }'"], shell=True)[0:-1] Oddly enough this line would only fail when the script was called by a shell script running from gammu-smsd. The line would fail with a CalledProcessError exception saying "returned exit status 2", even though the output attribute of the CalledProcessError object contained the correct output. The only command in the sequence of shell commands that would give such an error status would be awk, with status 2 indicating a fatal error. If the python script with this line was called by cron, by another python script, or from the command line, this line would work fine. I broke my head trying to fix the environment for the script, thinking this must be the problem. Finally though I put in stderr=subprocess.STDOUT, like so: reportdict['Used Space'] = subprocess.check_output(["df / | tail -1 | awk '{ print $5; }'"], stderr=subprocess.STDOUT, shell=True)[0:-1] This was a debug measure to help me figure out if some output was coming on stderr. But after this the script started working, even when called from gammu-smsd! Why might this be the case? I ask for future reference when using subprocess...

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  • Objective-measures of the expressiveness of programming languages [closed]

    - by Casebash
    I am very interested in the expressiveness of different languages. Everyone who has programmed in multiple languages knows that sometimes a language allows you to express concepts which you can't express in other languages. You can have all kinds of subjective discussion about this, but naturally it would be better to have an objective measure. There do actually exist objective measures. One is Turing-Completeness, which means that a language is capable of generating any output that could be generated by following a sequential set of steps. There are also other lesser levels of expressiveness such as Finite State Automata. Now, except for domain specific languages, pretty much all modern languages are Turing complete. It is therefore natural to ask the following question: Can we can define any other formal measures of expressiveness which are greater than Turing completeness? Now of course we can't define this by considering the output that a program can generate, as Turing machines can already produce the same output that any other program can. But there are definitely different levels in what concepts can be expressed - surely no-one would argue that assembly language is as powerful as a modern object oriented language like Python. You could use your assembly to write a Python interpreter, so clearly any accurate objective measure would have to exclude this possibility. This also causes a problem with trying to define the expressiveness using the minimum number of symbols. How exactly to do so is not clear and indeed appears extremely difficult, but we can't assume that just because we don't know how to solve a problem, that nobody know how to. It is also doesn't really make sense to demand a definition of expressiveness before answering the question - after all the whole point of this question is to obtain such a definition. I think that my explanation will be clear enough for anyone with a strong theoretical background in computer science to understand what I am looking for. If you do have such a background and you disagree, please comment why, but if you don't thats probably why you don't understand the question.

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  • How to filter http traffic in Wireshark?

    - by par
    I suspect my server has a huge load of http requests from its clients. I want to measure the volume of http traffic. How can I do it with Wireshark? Or probably there is an alternative solution using another tool? This is how a single http request/response traffic looks in Wireshark. The ping is generated by WinAPI funciton ::InternetCheckConnection() Thanks!

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  • Linux users traffic measurement

    - by Claudiu
    I want to measure traffic(upload) made by each user on a linux system. Each users runs a rTorrent instance on a specified port. Also users could make traffic through the ftp server (vsftpd). Is there a tool that can monitor traffic for a specified port and for ftp users ?

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  • network endpoint accessible via hostname only, not address?

    - by Dustin Getz
    someone told me that this piece of network hardware (NAS) has a security setting such that it can only be accessed by hostname, not by IP address. I don't understand, as I thought DNS resolved the hostname to an address on the connecting client's side, then at protocol level always used the raw address, so how can this 'security' measure be possible?

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  • Program that can count the most frequently used keys pressed on keyboard?

    - by sunpech
    Any recommendations on a program that I can manually start/stop to run in the background that will measure (count) how many times a key is pressed on the keyboard? As a software developer, I'd like to know which keys are used the most when I develop from project to project and/or from language to language. I'd like to be able to manually start and stop the program. This is for a Windows PC (xp, vista, 7)

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  • How to get higher download rate than upload rate

    - by user23950
    i'm using bandwidthplace.com to measure my internet speed. And here it is: Download Speed: 422 kbps (52.8 KB/sec transfer rate) Upload Speed: 202 kbps (25.3 KB/sec transfer rate) Can you please explain to me how did they get the 52.8 transfer rate. And how do I get to lower the upload speed in order for me to get higher download speed.

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  • SSD with multiple partitions - disk life implications

    - by Nicolas Webb
    Each block on a SSD has a finite number of writes. This is mitigated on modern drives by "spreading" the writes around as you use the drive. I'm wondering if you partition a SSD into several partitions (a Mac using Boot Camp, for example) if this measure is defeated somewhat - can the writes be spread across the entire drive? Or are they contained strictly within the partition boundaries? Any SSD controller engineers here :)?

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  • ab benchmarking testing

    - by Tennyson
    I have a question about ab benchmarking test, if i need to measure the time the server takes to serve IO.php with persistent connection. does the persistent connection mean i need to input "./ab -k ........." or "./ab -n 1000 -c 100 ........." Thanks a lot

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  • Powershell Exchange script returning inconsistent results - PS weirdness

    - by Ian
    Maybe someone can shed some light on a bit of Powershell weirdness I've come across and can't explain. This PS script returns a list of exchange databases, their sizes and the number of mailboxes in each one: Get-MailboxDatabase | Select Server, StorageGroupName, Name, @{Name="Size (GB)";Expression={$objitem = (Get-MailboxDatabase $_.Identity); $path = "`\`\" + $objitem.server + "`\" + $objItem.EdbFilePath.DriveName.Remove(1).ToString() + "$"+ $objItem.EdbFilePath.PathName.Remove(0,2); $size = ((Get-ChildItem $path).length)/1048576KB; [math]::round($size, 2)}}, @{Name="Size (MB)";Expression={$objitem = (Get-MailboxDatabase $_.Identity); $path = "`\`\" + $objitem.server + "`\" + $objItem.EdbFilePath.DriveName.Remove(1).ToString() + "$"+ $objItem.EdbFilePath.PathName.Remove(0,2); $size = ((Get-ChildItem $path).length)/1024KB; [math]::round($size, 2)}}, @{Name="No. Of Mbx";expression={(Get-Mailbox -Database $_.Identity | Measure-Object).Count}} | Format-table –AutoSize If I add a simple 'sort name' before the 'format-table' my resulting table contains blanks where the database sizes and number of mailboxes should appear (not zeros, blank empty space).... but only in some rows, not all rows. Some rows contain numbers! If I put the '|sort name| ' after the initial 'get-mailboxdatabase' it works fine. Whats even weirder is if I do the following: Execute the above command Add the sort before format-table Execute the new command Execute the initial command again What I see is different amounts in each of the three cases - all of which are incorrect. Yet 1 and 3 are the same command and the only difference with 2 is a sort. 1 and 3 should, at a minimum, return the same results. I get blanks where I should have MBs If I add the sort after the get-mailboxdatabase, it always returns identical results (as it should). Can anyone suggest an explanation as to what may be going on? If its of any help in reading the expression, I've reformatted it here to make it a bit more readable: Get-MailboxDatabase | Select Server, StorageGroupName, Name, @{Name="Size (GB)";Expression={ $objitem = (Get-MailboxDatabase $_.Identity); $path = "`\`\" + $objitem.server + "`\" + $objItem.EdbFilePath.DriveName.Remove(1).ToString() + "$" + $objItem.EdbFilePath.PathName.Remove(0,2); $size = ((Get-ChildItem $path).length)/1048576KB; [math]::round($size, 2) }}, @{Name="Size (MB)";Expression={ $objitem = (Get-MailboxDatabase $_.Identity); $path = "`\`\" + $objitem.server + "`\" + $objItem.EdbFilePath.DriveName.Remove(1).ToString() + "$" + $objItem.EdbFilePath.PathName.Remove(0,2); $size = ((Get-ChildItem $path).length)/1024KB; [math]::round($size, 2) }}, @{Name="No. Of Mbx";expression={ (Get-Mailbox -Database $_.Identity | Measure-Object).Count }} | Format-table –AutoSize

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  • What advantage does a 2400x600 dpi printer have over a 1200x1200 dpi printer?

    - by Cygon
    I've seen laser printers with a resolutions of 1200x1200 dpi and, strangely, 2400x600 dpi. As the measure is dots per inch, not Kdots on a page or something (where a higher vertical resolution might make sense because paper is rectangular, not square), I'm wondering what the uneven resolution is good for. Why print one square inch with 2400 dots vertically but only 600 horizontally? Does this look more detailed than 1200 by 1200 dots? Or is it better for textile printing or some other special case?

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  • Linux tools to choose suitable Cisco ASA 5500

    - by linuxcore
    I have a linux webhosting server which affects a high DDOS. I want to use Cisco ASA 5500 Series Adaptive Security Appliances to protect the linux server from this DDOS. I know there are many factors should you know before you choose the suitable hardware firewall like the amount of this DDOS and pps ..etc Please suggest a linux tools to measure those factors and to help me collect the required informations ( pps - amount of DDOS - concurrent connections and other factors ) Regards,

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  • The real differences between Red Hat Enterprise Linux (RHEL) and CentOS

    - by w00binda
    I know that "the vast majority of changes made (by CentOS team ndr) will be made to comply with the upstream vendor's re-distribution policies concerning trademarked names or logos" But I'm looking for a way to measure the real differences between RHEL and CentOS. My goal is to demonstrate "scientifically" that is possibile to use CentOS for development and testing purpose and use RHEL in the production environment. Any suggestion? Thanks in advance.

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  • How to circumvent ISP Limiting "Unknown" traffic - (SSH)Proxy, VPN

    - by connery
    I am having issues with using a proxy/VPN, with my current ISP (Comenersol, Spain). From my point of view they limit traffic by protocol or by traffic they "know" and "dont know". I'll explain my findings so far below. Internet connection in Spain: ~400-420KByte/sec (speedtest.net) OpenVPN Server in Sweden(pfsense): 100/100Mbit. LZO Compression. TCP. Tun. Aes128 Squid Proxy server in Sweden (pfsense): 100/100 (same box as the vpn server). Plain, no encryption. Runs in stealth mode to hide the use of proxy. NOT running OpenVPN or Squid Proxy, this is my findings: When I download a file from my pfsense box in Sweden, I get maximum speed When I run speedtest.net and choose any european server (including Swedish), I get max speed When I download a torrent (with non default port above 10K), I get limited to ~100KByte/sec. Encryption is turned off If I download something through https, I get max speed Running either Squid Proxy or VPN, this is my findings When I download a file from my pfsense box in Sweden, I get ~100KByte/sec When I run speedtest.net and choose any european server (including Swedish and Spanish), I get ~100Kbyte/sec When I download a torrent, I get same limitation ~100KByte/sec When I download something through https, I get ~100KByte/sec I verify the speeds above with speedtest.net measure, firefox measure in addition to having bmon running in terminal in the background. This way I am certain that the speeds I get presented, are in fact correct. If I connect through a different ISP with VPN or Squid Proxy, I get better speeds (400KByte/sec ++) In short: Whenever I tunnel my traffic through Sweden, my SPanish ISP throttles the traffic. I thought tunneling it through Squid would solve the issue, since I then would no longer hide my traffic through encryption. This does not seem to be the case. Wget and fetch gives same result. I did not try 'nc', but I assume this would give the same result. Does anyone know how to circumvent this issue? I would very much like to be able to get full speed with Swedish ip, as this would make me able to stream TV at higher quality than today. 100KByte/sec just does not cut it quality wise. Thanks for reading. Looking forward for your help.

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