[Lustre-discuss] Lustre slow file open close on RHEL5

[Mag Gam]

Can you check if you have readahead enabled?

http://manual.lustre.org/manual/LustreManual16_HTML/LustreProc.html#50557055_78950

This could probably be your cause.


On Thu, Nov 12, 2009 at 3:03 PM, Wojciech Turek <wjt27 at cam.ac.uk> wrote:
> Hi,
>
> Cluster running Lustre 1.6.6
> Opening and closing files takes longer on RHEL5 than on RHEL4. This is only
> happens with files located on Lustre file system. To reproduce this problem
> I used small C code (located on the bottom of my email).
> Is this a known problem? I will be grateful for any suggestions.
>
> RH4
> ====
> real    6m24.951s
> user    0m1.113s
> sys     0m43.983s
>
> real    3m21.464s
> user    0m1.011s
> sys     0m41.795s
>
> real    3m15.305s
> user    0m0.685s
> sys     0m34.321s
>
> real    3m52.444s
> user    0m1.073s
> sys     0m41.246s
>
> RH5
> ====
> real    6m56.701s
> user    0m0.602s
> sys     0m52.233s
>
> real    5m28.310s
> user    0m0.613s
> sys     0m48.284s
>
> real    5m19.244s
> user    0m0.555s
> sys     0m44.684s
>
> real    6m9.290s
> user    0m0.613s
>
>
> openclose.c
> ======
> #include <stdio.h>
> #include <stdlib.h>
>
> int openClose() {
>   FILE *fp;
>
>   if((fp = fopen("test.dat", "w+")) == NULL) {
>     printf("open error\n");
>     exit(1);
>   }
>
>   if( fclose( fp )) {
>     printf("close error\n");
>   }
>
>   return 0;
> }
>
> int main(void) {
>   int i;
>   for(i = 0; i < 300000; i++) {
>     openClose();
>   }
> }
>
> --
> --
> Wojciech Turek
>
> Assistant System Manager
>
> High Performance Computing Service
> University of Cambridge
> Email: wjt27 at cam.ac.uk
> Tel: (+)44 1223 763517
>
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>