linux-kernel - Re: [PATCH] mmu notifiers #v8

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Date:	Mon, 03 Mar 2008 20:09:49 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Jack Steiner <steiner@....com>
CC:	Nick Piggin <npiggin@...e.de>,
	Andrea Arcangeli <andrea@...ranet.com>,
	akpm@...ux-foundation.org, Robin Holt <holt@....com>,
	Izik Eidus <izike@...ranet.com>,
	kvm-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	general@...ts.openfabrics.org,
	Steve Wise <swise@...ngridcomputing.com>,
	Roland Dreier <rdreier@...co.com>,
	Kanoj Sarcar <kanojsarcar@...oo.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	daniel.blueman@...drics.com, Christoph Lameter <clameter@....com>
Subject: Re: [PATCH] mmu notifiers #v8

Jack Steiner wrote:
> The range invalidates have a performance advantage for the GRU. TLB invalidates
> on the GRU are relatively slow (usec) and interfere somewhat with the performance
> of other active GRU instructions. Invalidating a large chunk of addresses with
> a single GRU TLBINVAL operation is must faster than issuing a stream of single
> page TLBINVALs.
>
> I expect this performance advantage will also apply to other users of mmuops.
>   

In theory this would apply to kvm as well (coalesce tlb flush IPIs, 
lookup shadow page table once), but is it really a fast path?  What 
triggers range operations for your use cases?

-- 
error compiling committee.c: too many arguments to function

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