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

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Message-ID: <20080728233455.GA2919@elte.hu>
Date:	Tue, 29 Jul 2008 01:34:55 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Jens Axboe <jens.axboe@...cle.com>, Andi Kleen <ak@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: x86: Is there still value in having a special tlb flush IPI
	vector?


* Jeremy Fitzhardinge <jeremy@...p.org> 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.)

yep, and we could eliminate the reschedule IPI as well.

	Ingo
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