NFS on 10G interface terribly slow

Gerrit Kühn gerrit.kuehn at
Mon Jun 29 07:35:44 UTC 2015

On Fri, 26 Jun 2015 19:58:42 -0400 (EDT) Rick Macklem
<rmacklem at> wrote about Re: NFS on 10G interface terribly slow:

RM> The default (auto tuned) value is reported by "nfsstat -m".
RM> It can be set with a mount option (should be something in "man
RM> mount_nfs"). If you are doing a test with 1 megabyte writes, I'd set
RM> it to at least 1 megabyte. (Basically, writing will be slower for write
RM> (2) syscalls that are larger than wcommitsize. After mav@'s patch, the
RM> difference isn't nearly as noticable. His other commit makes the auto
RM> tuned value more reasonable).
RM> If you set it large enough with the "wcommitsize=<N>" mount option, you
RM> don't need the updates stable/10.

Ok, I set it way over 1MB now:

hellpool:/samqfs/K1/Gerrit on /net/hellpool

However, this still gives me the same bad write performance:

root at crest: # dd if=/dev/zero of=/net/hellpool/Z bs=1024k
count=1000 1000+0 records in
1000+0 records out
1048576000 bytes transferred in 22.939049 secs (45711398 bytes/sec)

So I guess I can postpone the update for now, and look for some other
reason for this instead.


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