Messages in this thread | | | Date | Thu, 11 Sep 2008 13:17:55 -0700 | From | "Priyank Patel" <> | Subject | Re: 2.6.26.3 kernel - progressive slowdown over NFS |
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Resending. Any pointers to other lists or more specific information which might be required ?
Thanks, -P
PS : Please cc me on the response.
On Tue, Sep 9, 2008 at 5:47 PM, Priyank Patel <pkpatel.lists@gmail.com> wrote: > Hi, > > > We have a simple python program which keeps running a C loop to lstat > NFS mounted directories. We are seeing some weird behavior w.r.t. the > run-time of this program on 2.6.26.3 kernel vs 2.6.24 kernel. > > The run-time of the following code increases over time on the 2.6.26.3 > kernel, whereas remains flat (as expected) on the 2.6.24 kernel. > [See attached graphs - B1.jpg and B2.jpg] Once the 2.6.26.3 machine > gets into this state, we need to restart the box to get back to > reasonable run-times. Is this a known issue ? > > Setup : > > Machine A (2.6.26) : exports NFS directory - /a/baz contains 10,000 > directories bar0 ... bar9999 > /a/baz *(rw,sync,no_root_squash,no_all_squash,subtree_check) > > Machine B1 (2.6.26.3) : mounts NFS dir RO from A - graph B1.jpg > 10.x.x.x:/a/baz on /baz type nfs > (ro,vers=3,rsize=4096,wsize=4096,namlen=255,hard,nointr,nolock,proto=udp,timeo=11,retrans=2,sec=sys,mountproto=udp,addr=10.x.x.x) > > Machine B2 (2.6.24) : mounts NFS dir RO from A - graph B2.jpg > 10.x.x.x:/a/baz on /baz type nfs > (ro,vers=3,rsize=4096,wsize=4096,hard,nointr,nolock,proto=udp,timeo=11,retrans=2,sec=sys,addr=10.x.x.x) > > Repro : > > B1 and B2, run the following python program : > {{{ > #!/usr/bin/env python > > import os > import sys > import time > > while True: > t1 = time.time() > rv = os.system("/a.out 10000 >& /dev/null") # lstat the 10000 > directories mounted via NFS > t2 = time.time() > print >> sys.stderr, "%.3f" % (t2 - t1), rv > }}} > > where a.out is the following C code : > > {{{ > #include <stdio.h> > #include <stdlib.h> > #include <sys/types.h> > #include <sys/stat.h> > #include <unistd.h> > > int main(int argc, char **argv) > { > int i, n = atoi(argv[1]); > char filename[64]; > struct stat statbuf; > > for (i = 0; i < n; i++) { > sprintf(filename, "/baz/bar%d", i); > lstat(filename, &statbuf); > } > > printf("done\n"); > return 0; > } > }}} > > Attachments : > > B1.jpg and B2.jpg - runtimes on the 2 client machines - > X-axis : iteration number > Y-axis : run-time > > Config files : - for the machines B1, B2 and A > > b1.2.6.26.3.config > b2.2.6.24.config > a.2.6.26.config > > > - P >
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