From: "Jan Beulich" <JBeulich@suse.com>
To: "Ian Campbell" <Ian.Campbell@citrix.com>,
"Imre Palik" <imrep.amz@gmail.com>
Cc: "Anthony Liguori" <aliguori@amazon.com>,
"Imre Palik" <imrep@amazon.de>,
"David Vrabel" <david.vrabel@citrix.com>, <x86@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
<xen-devel@lists.xenproject.org>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Ingo Molnar" <mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH RFC] xen-time: decreasing the rating of the xen clocksource below that of the tsc clocksource for dom0's
Date: Wed, 07 Jan 2015 16:57:27 +0000 [thread overview]
Message-ID: <54AD7387020000780005271C@mail.emea.novell.com> (raw)
In-Reply-To: <1420648234.18631.117.camel@citrix.com>
>>> On 07.01.15 at 17:30, <Ian.Campbell@citrix.com> wrote:
> On Wed, 2015-01-07 at 17:16 +0100, Imre Palik wrote:
>> From: "Palik, Imre" <imrep@amazon.de>
>>
>> In Dom0's the use of the TSC clocksource (whenever it is stable enough to
>> be used) instead of the Xen clocksource should not cause any issues, as
>> Dom0 VMs never live-migrated.
>
> Is this still true given that dom0's vcpus are migrated amongst pcpus on
> the host? The tsc are not synchronised on some generations of hardware
> so the result there would be the TSC appearing to do very odd things
> under dom0's feet. Does Linux cope with that or does it not matter for
> some other reason?
Indeed. The textual qualification above ("whenever it is stable enough")
isn't being expressed in the code change at all.
Jan
next prev parent reply other threads:[~2015-01-07 16:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-07 16:16 Imre Palik
2015-01-07 16:30 ` [Xen-devel] " Ian Campbell
2015-01-07 16:57 ` Jan Beulich [this message]
2015-01-08 15:06 ` Imre Palik
2015-01-12 11:30 ` David Vrabel
2015-01-07 16:59 ` Boris Ostrovsky
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