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Date: Thu, 19 Jun 2008 10:57:00 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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To: benh@kernel.crashing.org
CC: Linus Torvalds <torvalds@linux-foundation.org>,
       xen-devel <xen-devel@lists.xensource.com>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
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       Hugh Dickins <hugh@veritas.com>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 1 of 4] mm: add a ptep_modify_prot	transaction	abstraction
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Benjamin Herrenschmidt wrote:
>> Which architecture are you interested in?  If it isn't x86, you can 
>> probably get anything past Linus ;)
>>
>> I'll do some measurements to see what effect the batchable 
>> ptep_set_wrprotect() has on native.  If it's significant, I'll propose 
>> making it conditional on CONFIG_PARAVIRT.
>>     
>
> Oh, I mostly think about powerpc, I just wondered if I could re-use
> your new stuff in that context. Mostly idle thoughts at this stage, I
> haven't looked seriously.
>   

There are general-purpose hooks in the common code which architectures 
can implement however they like.  In x86-land we hook them up to pvops, 
but you can handle them however you want.

> I have an old patch set to batch forks (and mprotect etc...) TLB
> invalidations (which is what I really want to batch on powerpc, more
> than the actual PTE changes) that involves subtle changes to the
> batching mechanisms etc...
>   

Do you mean setting up batches of per-page tlb shootdowns rather than 
going a global tlb flush at the end?

    J