Re: [PATCH 0/33] KVM: MMU: Cache shadow page tables [LWN.net]

From:		Ingo Molnar <mingo-X9Un+BFzKDI-AT-public.gmane.org>
To:		Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w-AT-public.gmane.org>
Subject:		Re: [PATCH 0/33] KVM: MMU: Cache shadow page tables
Date:		Thu, 4 Jan 2007 19:02:23 +0100
Cc:		Andrew Morton <akpm-3NddpPZAyC0-AT-public.gmane.org>, kvm-devel <kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f-AT-public.gmane.org>, linux-kernel <linux-kernel-u79uwXL29TY76Z2rM5mHXA-AT-public.gmane.org>


* Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:

> Andrew Morton wrote:
> >Is this intended for 2.6.20, or would you prefer that we release what we
> >have now and hold this off for 2.6.21?
> >  
> 
> Even though these patches are potentially destabilazing, I'd like them 
> (and a few other patches) to go into 2.6.20:
> 
> - kvm did not exist in 2.6.19, hence we cannot regress from that
> - this patchset is the difference between a working proof of concept and 
> a generally usable system
> - from my testing, it's quite stable

seconded - i have tested the new MMU changes quite extensively and they 
are converging nicely. It brings down context-switch costs by a factor 
of 10 and more, even for microbenchmarks: instead of throwing away the 
full shadow pagetable hiearchy we have worked so hard to construct this 
patchset allows the intelligent caching of shadow pagetables. The effect 
is human-visible as well - the system got visibly snappier.

(I'd increase the shadow cache pool from the current 256 pages to at 
least 1024 pages, but that's a detail.)

Acked-by: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>

	Ingo

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