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

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Message-Id: <1217328351.7563.12.camel@twins>
Date:	Tue, 29 Jul 2008 12:45:51 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Nick Piggin <nickpiggin@...oo.com.au>
Cc:	Ingo Molnar <mingo@...e.hu>, Jeremy Fitzhardinge <jeremy@...p.org>,
	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?

On Tue, 2008-07-29 at 20:00 +1000, Nick Piggin wrote:
> On Tuesday 29 July 2008 19:54, Peter Zijlstra wrote:
> > On Tue, 2008-07-29 at 14:30 +1000, Nick Piggin wrote:
> > > Not to mention the minor problem that it still deadlocks when called with
> > > interrupts disabled ;)
> >
> > __smp_call_function_single has potential though..
> 
> For reschedule interrupt? I don't really agree.

How about using just arch_send_call_function_single_ipi() to implement
smp_send_reschedule() ?

The overhead of that is a smp_mb() and a list_empty() check in
generic_smp_call_function_single_interrupt() if there is indeed no work
to do.



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