Thank you for you email,<br><br>Yes readahead is enabled and it set to it's default value. Settings are exactly the same on RHEL4 and RHEL5 nodes.<br><br>Cheers<br><br>W<br><br><div class="gmail_quote">2009/11/15 Mag Gam <span dir="ltr"><<a href="mailto:magawake@gmail.com">magawake@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Can you check if you have readahead enabled?<br>
<br>
<a href="http://manual.lustre.org/manual/LustreManual16_HTML/LustreProc.html#50557055_78950" target="_blank">http://manual.lustre.org/manual/LustreManual16_HTML/LustreProc.html#50557055_78950</a><br>
<br>
This could probably be your cause.<br>
<div><div></div><div class="h5"><br>
<br>
On Thu, Nov 12, 2009 at 3:03 PM, Wojciech Turek <<a href="mailto:wjt27@cam.ac.uk">wjt27@cam.ac.uk</a>> wrote:<br>
> Hi,<br>
><br>
> Cluster running Lustre 1.6.6<br>
> Opening and closing files takes longer on RHEL5 than on RHEL4. This is only<br>
> happens with files located on Lustre file system. To reproduce this problem<br>
> I used small C code (located on the bottom of my email).<br>
> Is this a known problem? I will be grateful for any suggestions.<br>
><br>
> RH4<br>
> ====<br>
> real 6m24.951s<br>
> user 0m1.113s<br>
> sys 0m43.983s<br>
><br>
> real 3m21.464s<br>
> user 0m1.011s<br>
> sys 0m41.795s<br>
><br>
> real 3m15.305s<br>
> user 0m0.685s<br>
> sys 0m34.321s<br>
><br>
> real 3m52.444s<br>
> user 0m1.073s<br>
> sys 0m41.246s<br>
><br>
> RH5<br>
> ====<br>
> real 6m56.701s<br>
> user 0m0.602s<br>
> sys 0m52.233s<br>
><br>
> real 5m28.310s<br>
> user 0m0.613s<br>
> sys 0m48.284s<br>
><br>
> real 5m19.244s<br>
> user 0m0.555s<br>
> sys 0m44.684s<br>
><br>
> real 6m9.290s<br>
> user 0m0.613s<br>
><br>
><br>
> openclose.c<br>
> ======<br>
> #include <stdio.h><br>
> #include <stdlib.h><br>
><br>
> int openClose() {<br>
> FILE *fp;<br>
><br>
> if((fp = fopen("test.dat", "w+")) == NULL) {<br>
> printf("open error\n");<br>
> exit(1);<br>
> }<br>
><br>
> if( fclose( fp )) {<br>
> printf("close error\n");<br>
> }<br>
><br>
> return 0;<br>
> }<br>
><br>
> int main(void) {<br>
> int i;<br>
> for(i = 0; i < 300000; i++) {<br>
> openClose();<br>
> }<br>
> }<br>
><br>
> --<br>
> --<br>
> Wojciech Turek<br>
><br>
> Assistant System Manager<br>
><br>
> High Performance Computing Service<br>
> University of Cambridge<br>
> Email: <a href="mailto:wjt27@cam.ac.uk">wjt27@cam.ac.uk</a><br>
> Tel: (+)44 1223 763517<br>
><br>
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><br>
><br>
</blockquote></div><br><br clear="all"><br>-- <br>--<br>Wojciech Turek<br><br>Assistant System Manager<br><br>High Performance Computing Service<br>University of Cambridge<br>Email: <a href="mailto:wjt27@cam.ac.uk">wjt27@cam.ac.uk</a><br>
Tel: (+)44 1223 763517 <br>