Subject: Re: [RFC][PATCH] irq_work
From: Huang Ying <ying.huang@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, "H.PeterA" <"nvin hpa"@zytor.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Andi Kleen <andi@firstfloor.org>
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Date: Thu, 24 Jun 2010 15:27:33 +0800
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On Thu, 2010-06-24 at 15:19 +0800, Peter Zijlstra wrote:
> On Thu, 2010-06-24 at 15:04 +0800, Huang Ying wrote:
> 
> > Yes. NMI is there from 8259 age.
> 
> But do we really care about such systems?
> 
> > That is possible. But in NO_HZ system, we have no tick to rely on.
> 
> Of course you have, you can delay the NO_HZ state when there's pending
> callbacks, that's all of 1 line.
> 
> > soft_irq is better here, because it will be triggered for any interrupt.
> 
> Well, you can do the callbacks from irq_exit() as well, that's no
> problem.

I think it is not a good idea to add overhead in such a hot path if the
overhead can be avoided.

Best Regards,
Huang Ying


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