From: "Jan Beulich" <JBeulich@suse.com>
To: "Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"H. Peter Anvin" <hpa@zytor.com>
Cc: <cyclonusj@gmail.com>, <rostedt@goodmis.org>,
"Suresh B Siddha" <suresh.b.siddha@intel.com>,
<marmarek@invisiblethingslab.com>, <x86@kernel.org>,
<tglx@linutronix.de>, <xen-devel@lists.xensource.com>,
<mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
"Jason Garrett-Glaser" <jason@x264.com>
Subject: Re: [Xen-devel] [PATCH] x86 fixes for 3.3 impacting distros (v1).
Date: Thu, 28 Jun 2012 16:38:14 +0100 [thread overview]
Message-ID: <4FEC9686020000780008C9BB@nat28.tlf.novell.com> (raw)
In-Reply-To: <4FEC6D44.8080807@zytor.com>
>>> On 28.06.12 at 16:42, "H. Peter Anvin" <hpa@zytor.com> wrote:
> On 06/28/2012 07:28 AM, Konrad Rzeszutek Wilk wrote:
>> I also chatted with the core Xen hypervisor folks about adding in the
> context switch code
>> to alter the PAT layout - but they were not keen a about it - and I am not
> sure how much
>> CPU cycles one loses by doing a wrmsr to the PAT register on every guest
> context switch
>> (worst case when on has a pvops kernel and a old-style one - where the WC bit
> would differ)?
>>
>
> And you're comparing that to a bunch of new pvops calls? The discussion
> shouldn't even have started until you had ruled out this solution and
> had data to show it.
That's definitely not an option: Xen itself may be (and is, under
certain circumstances at least) using WC page table entries, so
we can't allow on-the-fly changes to the meaning of the various
indexes.
Jan
next prev parent reply other threads:[~2012-06-28 15:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-10 15:34 Konrad Rzeszutek Wilk
2012-02-10 15:34 ` [PATCH] x86/cpa: Use pte_attrs instead of pte_flags on CPA/set_p.._wb/wc operations Konrad Rzeszutek Wilk
2012-02-21 1:01 ` [PATCH] x86 fixes for 3.3 impacting distros (v1) Steven Rostedt
2012-02-21 1:38 ` H. Peter Anvin
2012-02-21 3:32 ` Konrad Rzeszutek Wilk
2012-02-22 2:53 ` Jason Garrett-Glaser
2012-05-10 15:34 ` [Xen-devel] " Konrad Rzeszutek Wilk
2012-06-27 23:17 ` Cyclonus J
2012-06-28 14:28 ` Konrad Rzeszutek Wilk
2012-06-28 14:42 ` H. Peter Anvin
2012-06-28 15:38 ` Jan Beulich [this message]
2012-06-29 21:52 ` Cyclonus J
2012-06-29 22:29 ` H. Peter Anvin
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