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 16:20:53 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Jens Axboe <jens.axboe@...cle.com>,
	Andi Kleen <andi@...stfloor.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: x86: Is there still value in having a special tlb flush IPI vector?

Resend to cc: Andi on an address which actually works.

Jeremy Fitzhardinge wrote:
> Now that normal smp_function_call is no longer an enormous bottleneck, 
> is there still value in having a specialised IPI vector for tlb 
> flushes?  It seems like quite a lot of duplicate code.
>
> The 64-bit tlb flush multiplexes the various cpus across 8 vectors to 
> increase scalability. If this is a big issue, then the smp function 
> call code can (and should) do the same thing.  (Though looking at it 
> more closely, the way the code uses the 8 vectors is actually a less 
> general way of doing what smp_call_function is doing anyway.)
>
> Thoughts?
>
> (And uv should definitely be hooking pvops if it wants its own 
> flush_tlb_others; vsmp sets the precedent for a subarch-like use of 
> pvops.)
>
>    J
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