Wojciech Turek
2009-Nov-12 20:03 UTC
[Lustre-discuss] Lustre slow file open close on RHEL5
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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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
2009-Nov-15 23:18 UTC
[Lustre-discuss] Lustre slow file open close on RHEL5
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 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.lustre.org/pipermail/lustre-discuss/attachments/20091115/93c28a9f/attachment.html