linux-kernel - Re: [PATCH 8/13] KVM: vcpu execution loop

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Message-ID: <69304d110610231508s73ee1bc5x7e8c1da37974d986@mail.gmail.com>
Date:	Tue, 24 Oct 2006 00:08:02 +0200
From:	"Antonio Vargas" <windenntw@...il.com>
To:	"Avi Kivity" <avi@...ranet.com>
Cc:	"Arnd Bergmann" <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 8/13] KVM: vcpu execution loop

On 10/23/06, Avi Kivity <avi@...ranet.com> wrote:
> Antonio Vargas wrote:
> >>
> >> I could do that, but I feel that's more brittle.  I might need more (or
> >> other) fields later on.  It will also cost me more  pushes on the stack
> >> (no real performance or space impact, just C64-era frugality).
> >
> > maybe thats the mindsent needed to make these virtual cpu patches
> > without eating away all the cpu power with more than needed
> > abstractions ;)
> >
>
> Unfortunately not.  Saving a cycle or two doesn't help when a vm exit
> costs thousands of cycles, and worse, kills your tlb.
>
> The key is eliminating unnecessary exits.  I have plans for massively
> optimizing the mmu virtualization, and the next AMD core will do that in
> hardware (look for a "nested page tables" sticker before you buy).

yes, when I read the nested pages description in amd docs, i wondered
that the intel had nothing like that and would go much slower... amd
has worked a lot on the mmu things (like cr3-keyed tlb on k8 systems
to avoid emptying always at switch)

> --
> Do not meddle in the internals of kernels, for they are subtle and quick to panic.
>
>


-- 
Greetz, Antonio Vargas aka winden of network

http://network.amigascne.org/
windNOenSPAMntw@...il.com
thesameasabove@...gascne.org

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you have to work
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