From: Lamia M.Y. <Lyo...@cs...> - 2004-07-02 08:43:18
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body> Hi All,<br> <pre class="moz-signature" cols="$mailwrapcol">I am kind of new to UML and I am experiencing a very strange performance hinder with it. I am running two benchmarks; one that writes a 50Mbyte file and the other one reads a 50Mbyte file. I tried the benchmarks with and without setting the O_DIRECT flag, in which cases the whole task is done in a matter of seconds(10-30 seconds) except when reading the file with O_DIRECT flag on. In this case, it takes 18-20 min!!! I am running UML 2.4.19 on top of kernel 2.4.25. I have time output like that (average of 20 runs) </pre> <table cellpadding="2" cellspacing="2" border="1" width="100%"> <tbody> <tr> <td valign="top"><b><font color="#000000">Operation<br> </font></b></td> <td valign="top"><b><font color="#000000">User Time (sec)<br> </font></b></td> <td valign="top"><b><font color="#000000">Sys Time(sec)<br> </font></b></td> <td valign="top"><b><font color="#000000">Wall Clock Time(sec)<br> </font></b></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Write Without O_DIRECT</font></b></pre> </td> <td valign="top"><font color="#000000">5.612000<br> </font></td> <td valign="top"><font color="#000000">0.117500<br> </font></td> <td valign="top"><font color="#000000">27.164500<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Write With O_DIRECT</font></b></pre> </td> <td valign="top"><font color="#000000">10.007000<br> </font></td> <td valign="top"><font color="#000000">0.017000<br> </font></td> <td valign="top"><font color="#000000">22.199500<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Read without O_DIRECT </font></b></pre> </td> <td valign="top"><font color="#000000">3.035000<br> </font></td> <td valign="top"><font color="#000000">0.091000<br> </font></td> <td valign="top"><font color="#000000">7.760000<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Read With O_DIRECT</font></b></pre> </td> <td valign="top"><b><font color="#ff0000">21.492000<br> </font></b></td> <td valign="top"><b><font color="#ff0000">29.680000<br> </font></b></td> <td valign="top"><b><font color="#ff0000">1133.054000<br> </font></b></td> </tr> </tbody> </table> <pre class="moz-signature" cols="$mailwrapcol"> I would appreciate it very much if somebody would explain to me how to solve that strange performance problem, or even explain why does it happen for reading with O_DIRECT but not without !!?? Thanks allot, Lamia Youseff -- </pre> </body> </html> |
From: Lamia M.Y. <Lyo...@cs...> - 2004-07-02 08:46:28
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> Hi All,<br> <pre class="moz-signature" cols="$mailwrapcol">I am kind of new to UML and I am experiencing a very strange performance hinder with it. I am running two benchmarks; one that writes a 50Mbyte file and the other one reads a 50Mbyte file. I tried the benchmarks with and without setting the O_DIRECT flag, in which cases the whole task is done in a matter of seconds(10-30 seconds) except when reading the file with O_DIRECT flag on. In this case, it takes 18-20 min!!! I am running UML 2.4.19 on top of kernel 2.4.25. I have time output like that (average of 20 runs) </pre> <table cellpadding="2" cellspacing="2" border="1" width="100%"> <tbody> <tr> <td valign="top"><b><font color="#000000">Operation<br> </font></b></td> <td valign="top"><b><font color="#000000">User Time (sec)<br> </font></b></td> <td valign="top"><b><font color="#000000">Sys Time(sec)<br> </font></b></td> <td valign="top"><b><font color="#000000">Wall Clock Time(sec)<br> </font></b></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Write Without O_DIRECT</font></b></pre> </td> <td valign="top"><font color="#000000">5.612000<br> </font></td> <td valign="top"><font color="#000000">0.117500<br> </font></td> <td valign="top"><font color="#000000">27.164500<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Write With O_DIRECT</font></b></pre> </td> <td valign="top"><font color="#000000">10.007000<br> </font></td> <td valign="top"><font color="#000000">0.017000<br> </font></td> <td valign="top"><font color="#000000">22.199500<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Read without O_DIRECT </font></b></pre> </td> <td valign="top"><font color="#000000">3.035000<br> </font></td> <td valign="top"><font color="#000000">0.091000<br> </font></td> <td valign="top"><font color="#000000">7.760000<br> </font></td> </tr> <tr> <td valign="top"> <pre class="moz-signature" cols="$mailwrapcol"><b><font color="#000000">Read With O_DIRECT</font></b></pre> </td> <td valign="top"><b><font color="#ff0000">21.492000<br> </font></b></td> <td valign="top"><b><font color="#ff0000">29.680000<br> </font></b></td> <td valign="top"><b><font color="#ff0000">1133.054000<br> </font></b></td> </tr> </tbody> </table> <pre class="moz-signature" cols="$mailwrapcol">I would appreciate it very much if somebody would explain to me how to solve that strange performance problem, or even explain why does it happen for reading with O_DIRECT but not without !!?? Thanks allot, Lamia Youseff -- </pre> </body> </html> |
From: <lyo...@cs...> - 2004-07-02 17:25:15
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Sorry for the repeated posts, but i figured out that my email body was not posted. My appologies for the spam. --------------------------------- Hi All, I am kind of new to UML and I am experiencing a very strange performance hinder with it. I am running two benchmarks; one that writes a 50Mbyte file and the other one reads a 50Mbyte file. I tried the benchmarks with and without setting the O_DIRECT flag, in which cases the whole task is done in a matter of seconds(10-30 seconds) except when reading the file with O_DIRECT flag on. In this case, it takes 18-20 min!!! I am running UML 2.4.19 on top of kernel 2.4.25. I have time output like that (average of 20 runs) Operation UserTime(sec) SysTime(sec) WallClockTime(sec) Write Without O_DIRECT 5.612000 0.117500 27.164500 Write With O_DIRECT 10.007000 0.017000 22.199500 Read without O_DIRECT 3.035000 0.091000 7.760000 Read With O_DIRECT 21.492000 29.680000 1133.054000 I would appreciate it very much if somebody would explain to me how to solve that strange performance problem, or even explain why does it happen for reading with O_DIRECT but not without !!?? Thanks allot, Lamia Youseff -- |
From: BlaisorBlade <bla...@ya...> - 2004-07-04 10:00:48
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Alle 10:42, venerd=EC 2 luglio 2004, Lamia M.Youseff ha scritto: > I am running UML 2.4.19 on top of kernel 2.4.25. I have time output like > that (average of 20 runs)=20 Well, could you try upgrading it to 2.4.24-1um and retesting? That UML is o= ld,=20 buggy, and outdated. =2D-=20 Paolo Giarrusso, aka Blaisorblade Linux registered user n. 292729 |
From: Lamia M.Y. <Lyo...@cs...> - 2004-07-06 05:34:27
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body> Hello All, Hi BlaisorBlade,<br> I upgraded to 2.4.24-1um, but the same error still persist on the um..i.e. the disk reads takes so long when used with the O_DIRECT flag !!<br> Anybody has any explanation for that??<br> <br> Thank you,<br> Lamia Youseff<br> <br> <br> BlaisorBlade wrote:<br> <blockquote type="cite" cite="mid...@ya..."> <pre wrap="">Alle 10:42, venerdì 2 luglio 2004, Lamia M.Youseff ha scritto: </pre> <blockquote type="cite"> <pre wrap="">I am running UML 2.4.19 on top of kernel 2.4.25. I have time output like that (average of 20 runs) </pre> </blockquote> <pre wrap=""><!---->Well, could you try upgrading it to 2.4.24-1um and retesting? That UML is old, buggy, and outdated. </pre> </blockquote> <br> <pre class="moz-signature" cols="$mailwrapcol">-- .......................................................... : Lamia M.Youseff : <a class="moz-txt-link-abbreviated" href="mailto:lyo...@cs...">lyo...@cs...</a> : : Ph.D student : <a class="moz-txt-link-abbreviated" href="http://www.cs.ucsb.edu/~lyouseff">www.cs.ucsb.edu/~lyouseff</a> : : University of California,: : : Santa Barbara (UCSB) : : :........................................................: : : : "There are no impossible dreams; there is just our : : limited perception of what is possible" : *:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-.,_,.-:*'``'*:-.,_,.-:*'*</pre> <br> </body> </html> |