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

[Wojciech Turek]

Thank you for you email,

Yes readahead is enabled and it set to it's default value. Settings are
exactly the same on RHEL4 and RHEL5 nodes.

Cheers

W

2009/11/15 Mag Gam <magawake at gmail.com>

> 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
> >
> > _______________________________________________
> > Lustre-discuss mailing list
> > Lustre-discuss at lists.lustre.org
> > http://lists.lustre.org/mailman/listinfo/lustre-discuss
> >
> >
>



-- 
--
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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