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

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Message-ID: <488F2D48.7030305@goop.org>
Date:	Tue, 29 Jul 2008 07:46:32 -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:
>> 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.
>>     
>
> If it bounces regularly it will still hurt.
>   

We could convert smp_call_function_mask to use a multi-vector scheme 
like tlb_64.c if that turns out to be an issue.

    J
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