linux-kernel - Re: [PATCH v5 6/7] x86/tlb: optimizing flush_tlb

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Message-ID: <1337093840.27694.56.camel@twins>
Date:	Tue, 15 May 2012 16:57:20 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Alex Shi <alex.shi@...el.com>
Cc:	Nick Piggin <npiggin@...il.com>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, arnd@...db.de,
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	riel@...hat.com, luto@....edu, avi@...hat.com, len.brown@...el.com,
	dhowells@...hat.com, fenghua.yu@...el.com, borislav.petkov@....com,
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	kamezawa.hiroyu@...fujitsu.com, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, yongjie.ren@...el.com,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH v5 6/7] x86/tlb: optimizing flush_tlb_mm

On Tue, 2012-05-15 at 16:36 +0200, Peter Zijlstra wrote:
> On Tue, 2012-05-15 at 21:24 +0800, Alex Shi wrote:
> 
> > Sorry. I don't understand what's the comments Peter's made days ago. I should ask for more details originally. 
> > 
> > So, Peter, the correct change should like following, am I right?
> > 
> > -#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
> > +#define tlb_flush(tlb, start, end) __flush_tlb_range((tlb)->mm, start, end)
> 
> No.. the correct change is to do range tracking like the other archs
> that support flush_tlb_range() do.
> 
> You do not modify the tlb interface.
> 
> Again, see: http://marc.info/?l=linux-arch&m=129952026504268&w=2

Just to be _very_ clear, you do not modify:

 mm/memory.c                     |    9 ++--
 kernel/fork.c                   |    2 +-   
 fs/proc/task_mmu.c              |    2 +-

As it stands your patch breaks compilation on a whole bunch of
architectures.

If you touch the TLB interface, you get to touch _ALL_ architectures.
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