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From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: "Dong, Eddie" <eddie.dong-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel <kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
Subject: Re: [PATCH] Remove redundant MSR save/restore
Date: Wed, 25 Apr 2007 12:28:39 +0300	[thread overview]
Message-ID: <462F1F47.8020209@qumranet.com> (raw)
In-Reply-To: <10EA09EFD8728347A513008B6B0DA77A01599E01-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>

Dong, Eddie wrote:
> Avi:
> 	Thanks!
> 	Another found is that HOST_FS/GS_BASE & MSR_FS/GS_BASE
> save/restore is quit expansive. I am not sure why it needs to be
> save/restored given that the VMCS regster will be loaded into FS/gs at
> VM EXIT time automatically by HW and will not be changed during guest
> execution time. The MSR is also same (guest change will be trap and
> emulated in guest context only).
> 	If I remove HOST_FS/GS_BASE save/restore out to be only matter
> to userspace, I can get 15% performance gain for KB. But I am not sure
> yet if there is any potential issue.
> 	
> thanks, eddie
>   

I don't see issues with moving them outside the loop, as long as 
preemption is disabled.

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


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  parent reply	other threads:[~2007-04-25  9:28 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-23  2:56 [PATCH] Lazy FPU for SVM Anthony Liguori
     [not found] ` <462C2048.4040700-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-04-23  6:50   ` Avi Kivity
     [not found]     ` <462C574E.2030304-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-04-23 14:32       ` Anthony Liguori
     [not found]         ` <462CC380.5020405-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-04-24 10:39           ` Avi Kivity
     [not found]             ` <462DDE52.5040303-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-04-24 13:59               ` Anthony Liguori
     [not found]                 ` <462E0D52.5000707-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-04-24 14:32                   ` Avi Kivity
2007-04-25  8:03           ` [PATCH] Remove redundant MSR save/restore Dong, Eddie
     [not found]             ` <10EA09EFD8728347A513008B6B0DA77A01599D74-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-04-25  8:17               ` Avi Kivity
     [not found]                 ` <462F0E90.8010307-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-04-25  8:53                   ` Dong, Eddie
     [not found]                     ` <10EA09EFD8728347A513008B6B0DA77A01599E01-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-04-25  9:28                       ` Avi Kivity [this message]
2007-04-25  7:30   ` [PATCH] Remove heavy is_empty_shadow_page call Dong, Eddie
     [not found]     ` <10EA09EFD8728347A513008B6B0DA77A01599D2B-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-04-25  8:03       ` Avi Kivity
     [not found]         ` <462F0B40.9060109-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-04-25  8:09           ` Dong, Eddie
     [not found]             ` <10EA09EFD8728347A513008B6B0DA77A01599D87-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2007-04-25  8:20               ` Avi Kivity
2007-04-25  8:40       ` Michael Riepe
     [not found]         ` <462F13E0.80104-0QoEqw4nQxo@public.gmane.org>
2007-04-25  8:45           ` Dong, Eddie
2007-04-25  8:49           ` Avi Kivity

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