From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 08/20] mm: Optimize fullmm TLB flushing
Date: Fri, 29 Jun 2012 07:57:21 +1000
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Catalin Marinas <catalin.marinas@arm.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, Rik van Riel <riel@redhat.com>, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>, Alex Shi <alex.shi@intel.com>, "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>, Konrad Rzeszutek Wilk <konrad@darnok.org>, David Miller <davem@davemloft.net>, Russell King <rmk@arm.linux.org.uk>, Chris Metcalf <cmetcalf@tilera.com>, Martin
List-Id: linux-arch.vger.kernel.org

On Thu, 2012-06-28 at 18:52 +0200, Peter Zijlstra wrote:
> No I think you're right (as always).. also an IPI will not force
> schedule the thread that might be running on the receiving cpu, also
> we'd have to wait for any such schedule to complete in order to
> guarantee the mm isn't lazily used anymore.
> 
> Bugger.. 

You can still do it if the mm count is 1 no ? Ie, current is the last
holder of a reference to the mm struct... which will probably be the
common case for short lived programs.

Cheers,
Ben.


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