linux-kernel - Re: [RFC/PATCH] Use mmu_gather for fork() instead of flush_tlb

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Message-ID: <46920A0C.3040400@yahoo.com.au>
Date:	Mon, 09 Jul 2007 20:12:28 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	linux-mm@...ck.org,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [RFC/PATCH] Use mmu_gather for fork() instead of flush_tlb_mm()

Benjamin Herrenschmidt wrote:
> On Mon, 2007-07-09 at 19:29 +1000, Nick Piggin wrote:
> 
>>They could just #define one to the other though, there are only a
>>small
>>number of them. Is there a downside to not making them distinct? i386
>>for example probably would just keep doing a tlb flush for fork and
>>not
>>want to worry about touching the tlb gather stuff.
> 
> 
> But the tlb gather stuff just does ... a flush_tlb_mm() on x86 :-)

But it still does the get_cpu of the mmu gather data structure and
has to look in there and touch the cacheline. You're also having to
do more work when unlocking/relocking the ptl etc.


> I really think it's the right API



-- 
SUSE Labs, Novell Inc.
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