Message-ID: <49C16349.9030503@us.ibm.com>
Date: Wed, 18 Mar 2009 14:10:33 -0700
From: Vernon Mauery <vernux@us.ibm.com>
User-Agent: Thunderbird 2.0.0.19 (X11/20090105)
MIME-Version: 1.0
To: David Miller <davem@davemloft.net>
CC: andi@firstfloor.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
       linux-rt-users@vger.kernel.org
Subject: Re: High contention on the sk_buff_head.lock
References: <49C12E64.1000301@us.ibm.com> <87prge1rhu.fsf@basil.nowhere.org> <20090318.140340.55290859.davem@davemloft.net>
In-Reply-To: <20090318.140340.55290859.davem@davemloft.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1096
Lines: 27

David Miller wrote:
> From: Andi Kleen <andi@firstfloor.org>
> Date: Wed, 18 Mar 2009 21:54:37 +0100
> 
>> But then again I'm not sure it's  worth it if the problem only
>> happens in out of tree RT.
> 
> The list of problems that only show up with the RT kernel seems to be
> constantly increasing, but honestly is very surprising to me.
> 
> I don't understand why we even need to be concerned about this stuff
> upstream, to be honest.
> 
> Please reproduce this in the vanilla kernel, then get back to us.

Huh? The numbers that I posted *were* from the vanilla kernel. I ran
the 2.6.29-rc8 kernel with lock_stat enabled.  The lock contention
happens on the same lock in both vanilla and -rt, it just happens
to be more pronounced in the -rt kernel because of the double context
switches that the sleeping spinlock/rt-mutexes introduce.

--Vernon
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/