Messages in this thread |  | | Date | Wed, 2 Sep 2009 17:06:42 -0700 | From | Andrew Morton <> | Subject | Re: VM issue causing high CPU loads |
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On Mon, 31 Aug 2009 22:39:20 +0200 Yohan <ytordjman@corp.free.fr> wrote:
> Yohan wrote: > > Andrew Morton wrote: > >> On Mon, 24 Aug 2009 16:23:22 +0200 > >> Yohan <kernel@yohan.staff.proxad.net> wrote: > >>> Hi, > >>> > >>> Is someone have an idea for that : > >>> > >>> http://bugzilla.kernel.org/show_bug.cgi?id=14024 > >>> > >> Please generate a kernel profile to work out where all the CPU tie is > >> being spent. Documentation/basic_profiling.txt is a starting point. > >> > > I post some new reports, it seems that the problem is in > > rpcauth_lookup_credcache ...
Thanks, that helps a lot.
> > for information, this is an imap mail server that mounts ~10 netapp > > over ~300 mountpoints.. > I saw that : http://patchwork.kernel.org/patch/24747/
I wonder what happened with Miquel's patch?
> I did only: > > --- linux-2.6.27.21/include/linux/sunrpc/auth.h 2009-03-23 23:04:09.000000000 +0100 > +++ linux-2.6.27.21/include/linux/sunrpc/auth.h 2009-05-19 16:02:35.000000000 +0200 > @@ -62,8 +62,12 @@ > */ > - #define RPC_CREDCACHE_HASHBITS 4 > + #define RPC_CREDCACHE_HASHBITS 12 > > > And i test it in prod since sunday: i only have 36% of one core used by > system > versus more than 3 cores used by system in another server that did a > drop_caches at morning... >
OK, but it's still pretty bad. Let's tell the NFS guys.
In http://bugzilla.kernel.org/show_bug.cgi?id=14024 we appear to have a major meltdown caused by the linear search in rpcauth_lookup_credcache() with Yohan's workload.
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