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Date: Wed, 4 Apr 2007 13:54:58 +0200
From: Eric Dumazet <dada1@cosmosbay.com>
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Andrew Morton <akpm@linux-foundation.org>,
       Jakub Jelinek <jakub@redhat.com>, Ulrich Drepper <drepper@redhat.com>,
       Andi Kleen <andi@firstfloor.org>, Rik van Riel <riel@redhat.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
       Hugh Dickins <hugh@veritas.com>
Subject: Re: missing madvise functionality
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On Wed, 04 Apr 2007 20:05:54 +1000
Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> 
> > @@ -1638,7 +1652,7 @@ find_extend_vma(struct mm_struct * mm, u
> >  	unsigned long start;
> >  
> >  	addr &= PAGE_MASK;
> > -	vma = find_vma(mm,addr);
> > +	vma = find_vma(mm,addr,&current->vmacache);
> >  	if (!vma)
> >  		return NULL;
> >  	if (vma->vm_start <= addr)
> 
> So now you can have current calling find_extend_vma on someone else's mm
> but using their cache. So you're going to return current's vma, or current
> is going to get one of mm's vmas in its cache :P

This was not a working patch, just to throw the idea, since the answers I got showed I was not understood.

In this case, find_extend_vma() should of course have one struct vm_area_cache * argument, like find_vma()

One single cache on one mm is not scalable. oprofile badly hits it on a dual cpu config.