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From: David Vrabel <david.vrabel@citrix.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Jan Beulich <JBeulich@suse.com>,
	Konrad Wilk <konrad.wilk@oracle.com>,
	"Tim (Xen.org)" <tim@xen.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	xen-devel <xen-devel@lists.xen.org>,
	Sheng Yang <sheng@yasker.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [Xen-devel] [PATCH] xen: always set the sched clock as unstable
Date: Mon, 16 Apr 2012 17:26:00 +0100	[thread overview]
Message-ID: <4F8C4818.8070603@citrix.com> (raw)
In-Reply-To: <049b7b93-fb37-4962-b272-d786e1dcfacb@default>

On 16/04/12 17:05, Dan Magenheimer wrote:
>> From: David Vrabel [mailto:david.vrabel@citrix.com]
>> Subject: Re: [Xen-devel] [PATCH] xen: always set the sched clock as unstable
> 
> Nacked-by: Dan Magenheimer <dan.magenheimer@oracle.com>

Fair enough,

> [A stable clock] should be true for Xen 4.0+ (but not for pre-Xen-4.0).

The original customer problem is on a host with Xen 3.4.  What do you
recommend for Linux guests running such hosts?

> In fact, it might be wise for a Xen-savvy kernel to check to see
> if it is running on Xen-4.0+ and, if so, force clocksource=tsc
> and tsc=reliable.

So, should the xen clocksource do:

if Xen 4.0+
    clock is stable, use rdtsc only.
else
    clock is unstable, use existing pvclock implementation.

David

  parent reply	other threads:[~2012-04-16 16:29 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-13 18:20 [PATCH] xen: always set the sched clock as unstable David Vrabel
2012-04-13 18:33 ` Sheng Yang
     [not found] ` <CA+2rt41ctpU-vhR7=u_r45=o8djpq0-5YE5jcj_4FR2bWYu5pQ@mail.gmail.com>
2012-04-13 18:39   ` David Vrabel
2012-04-16 11:32 ` Jan Beulich
2012-04-16 14:59   ` David Vrabel
2012-04-16 15:16     ` Tim Deegan
2012-04-16 15:17     ` Konrad Rzeszutek Wilk
2012-04-16 16:20       ` [Xen-devel] " Dan Magenheimer
2012-04-16 16:05     ` Dan Magenheimer
2012-04-16 16:14       ` Jan Beulich
2012-04-16 17:22         ` Dan Magenheimer
2012-04-17  7:27           ` Jan Beulich
2012-04-17 15:36             ` Dan Magenheimer
2012-04-16 16:26       ` David Vrabel [this message]
2012-04-16 17:30         ` Dan Magenheimer
2012-04-17  7:47           ` Jan Beulich
2012-04-17 15:42             ` Dan Magenheimer
2012-04-16 17:08       ` Tim Deegan
2012-04-16 17:52         ` Dan Magenheimer
2012-04-16 18:17           ` Tim Deegan
2012-04-16 23:01             ` Sheng Yang
2012-04-17  0:29               ` Dan Magenheimer
2012-04-17  8:19               ` Tim Deegan

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