linux-kernel - Re: x86: Is there still value in having a special tlb flush IPI vector?

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Date:	Mon, 28 Jul 2008 23:29:18 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Ingo Molnar <mingo@...e.hu>, Jens Axboe <jens.axboe@...cle.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: x86: Is there still value in having a special tlb flush IPI vector?

Andi Kleen wrote:
>>> Now that normal smp_function_call is no longer an enormous bottleneck, 
>>>       
>
> Hmm? It still uses a global lock at least as of current git tree.

Yes, but it's only held briefly to put things onto the list.  It doesn't 
get held over the whole IPI transaction as the old smp_call_function 
did, and the tlb flush code still does.  RCU is used to manage the list 
walk and freeing, so there's no long-held locks there either.

    J
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