Re: VM issue causing high CPU loads

Yohan
2009-08-31T20:39:25Z

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 ...
>
> 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 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...

Yohan