Message-ID: <479E20DA.2080403@qualcomm.com>
Date: Mon, 28 Jan 2008 10:37:14 -0800
From: Max Krasnyanskiy <maxk@qualcomm.com>
User-Agent: Thunderbird 2.0.0.9 (X11/20071115)
MIME-Version: 1.0
To: Paul Jackson <pj@sgi.com>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-kernel@vger.kernel.org,
       mingo@elte.hu, srostedt@redhat.com, ghaskins@novell.com
Subject: Re: [CPUISOL] CPU isolation extensions
References: <1201493382-29804-1-git-send-email-maxk@qualcomm.com>	<1201511305.6149.30.camel@lappy> <20080128085910.7d38e9f5.pj@sgi.com>
In-Reply-To: <20080128085910.7d38e9f5.pj@sgi.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2036
Lines: 42

Paul Jackson wrote:
> Thanks for the CC, Peter.
> 
>   Ingo - see question at end of message.
> 
> Max wrote:
>> We've had scheduler support for CPU isolation ever since O(1) scheduler went it. 
>> I'd like to extend it further to avoid kernel activity on those CPUs as much as possible.
> 
> I recently added the per-cpuset flag 'sched_load_balance' for some
> other realtime folks, so that they can disable the kernel scheduler
> load balancing on isolated CPUs.  It essentially allows for dynamic
> control of which CPUs are isolated by the scheduler, using the cpuset
> hierarchy, rather than enhancing the 'isolated_cpus' mask.   That
> 'isolated_cpus' mask remained a minimal kernel boottime parameter.
> I believe this went to Linus's tree about Oct 2007.
> 
> It looks like you have three additional tweaks for realtime in this
> patch set, with your patches:
> 
>   [PATCH] [CPUISOL] Do not route IRQs to the CPUs isolated at boot
>   [PATCH] [CPUISOL] Support for workqueue isolation
>   [PATCH] [CPUISOL] Isolated CPUs should be ignored by the "stop machine"
> 
> It would be interesting to see a patchset with the above three realtime
> tweaks, layered on this new cpuset 'sched_load_balance' apparatus, rather
> than layered on changes to make 'isolated_cpus' more dynamic.  Some of us
> run realtime and cpuset-intensive loads on the same system, so like to
> have those two capabilities co-operate with each other.
I'll definitely take a look. So far it seems that extending cpu_isolated_map
is more natural way of propagating this notion to the rest of the kernel.
Since it's very similar to the cpu_online_map concept and it's easy to integrated
with the code that already uses it. 
Anyway. I'll take a look at the cpuset flag that you mentioned and report back.

Thanx
Max
--
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/