[Bug 1071978] Re: nfs kernel server is very slow and causing high cpu load

[Dave Gilbert]

OK; so we've got to be careful to keep the debug together; I think you really have two separate things going on:
  a) Slow when transferring lots of stuff (as per your vmstat in #9)
  b) 'hang up's

Is that perf report from the 'hang up' state - it doesn't seem to have
much system/kernel CPU usage - so I'm assuming that perf report (#13)
corresponds to the vmstat in #12 - is that correct?   (That perf doesn't
seem to show much doing anything - which again if it's that hang up
state when it's mostly idle/wait makes sense)

OK, so for (b) - have you got a dmesg from the server after a hangup?
The other thing I can suggest for (b) is to try reducing the 'dirty_ratio', it causes the kernel to start to write out to disk sooner;
try (as root):
    echo 2 > /proc/sys/vm/dirty_ratio

and see if that makes any difference to the hang up case.

Now, I think it's still worth investigating the (a) case - i.e. the high
cpu load when transferring a lot; if you can get a perf report for that
case it would be interesting to tie up.

Dave

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to nfs-utils in Ubuntu.
https://bugs.launchpad.net/bugs/1071978

Title:
  nfs kernel server is very slow and causing high cpu load

Status in “nfs-utils” package in Ubuntu:
  New

Bug description:
  I have been noticing nfs-kernel server causing very high cpu load and
  the transfers are incredibly slow. In fact for big files, it tends to
  hang up completely and never finish.

  I did try briefly to test the 3.5 backport kernel however that also
  seemed to have the same issue.

  This may be a duplication of bug #879334, however that bug is missing
  log files, and apport-collect told me to file a new bug report
  instead.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: nfs-kernel-server 1:1.2.5-3ubuntu3.1
  ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
  Uname: Linux 3.2.0-32-generic x86_64
  ApportVersion: 2.0.1-0ubuntu14
  Architecture: amd64
  Date: Sat Oct 27 14:50:09 2012
  InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120328)
  ProcEnviron:
   LANGUAGE=en_AU:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_AU.UTF-8
   SHELL=/bin/bash
  SourcePackage: nfs-utils
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1071978/+subscriptions