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    SubjectRe: 2.6.26.3 kernel - progressive slowdown over NFS
    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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