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From: Suresh Siddha <suresh.b.siddha@intel.com>
To: Avi Kivity <avi@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Brian Gerst <brgerst@gmail.com>,
	"Cui, Dexuan" <dexuan.cui@intel.com>,
	Sheng Yang <sheng@linux.intel.com>, Ingo Molnar <mingo@elte.hu>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 1/2] x86: eliminate TS_XSAVE
Date: Tue, 04 May 2010 11:15:27 -0700	[thread overview]
Message-ID: <1272996927.2833.13.camel@sbs-t61.sc.intel.com> (raw)
In-Reply-To: <4BDFCF9F.3030600@redhat.com>

On Tue, 2010-05-04 at 00:41 -0700, Avi Kivity wrote:
> On 05/04/2010 12:45 AM, H. Peter Anvin wrote:
> >
> >> I was trying to avoid a performance regression relative to the current
> >> code, as it appears that some care was taken to avoid the memory reference.
> >>
> >> I agree that it's probably negligible compared to the save/restore
> >> code.  If the x86 maintainers agree as well, I'll replace it with
> >> cpu_has_xsave.
> >>
> >>      
> > I asked Suresh to comment on this, since he wrote the original code.  He
> > did confirm that the intent was to avoid a global memory reference.
> >
> >    
> 
> Ok, so you're happy with the patch as is?

As use_xsave() is in the hot context switch path, I would like to go
with Avi's proposal.

thanks,
suresh


  reply	other threads:[~2010-05-04 18:16 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-02 14:53 [PATCH 0/2] x86 FPU API Avi Kivity
2010-05-02 14:53 ` [PATCH 1/2] x86: eliminate TS_XSAVE Avi Kivity
2010-05-02 17:38   ` Brian Gerst
2010-05-02 17:44     ` Avi Kivity
2010-05-03 21:45       ` H. Peter Anvin
2010-05-04  7:41         ` Avi Kivity
2010-05-04 18:15           ` Suresh Siddha [this message]
2010-05-04 18:24             ` H. Peter Anvin
2010-05-05  7:30               ` Avi Kivity
2010-05-05 12:10                 ` H. Peter Anvin
2010-05-05 12:12                 ` H. Peter Anvin
2010-05-04 18:03   ` Suresh Siddha
2010-05-02 14:53 ` [PATCH 2/2] x86: Introduce 'struct fpu' and related API Avi Kivity
2010-05-04 18:12   ` Suresh Siddha

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