linux-kernel - Re: VM issue causing high CPU loads

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Message-ID: <4A9C34F8.2010307@corp.free.fr>
Date:	Mon, 31 Aug 2009 22:39:20 +0200
From:	Yohan <ytordjman@...p.free.fr>
To:	Yohan <ytordjman@...p.free.fr>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: VM issue causing high CPU loads

Yohan wrote:
> Andrew Morton wrote:
>> On Mon, 24 Aug 2009 16:23:22 +0200
>> Yohan <kernel@...an.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
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