From: Jan Beulich <jbeulich@suse.com>
To: Igor Druzhinin <igor.druzhinin@citrix.com>
Cc: xen-devel@lists.xenproject.org, roger.pau@citrix.com, wl@xen.org,
andrew.cooper3@citrix.com
Subject: Re: [Xen-devel] [PATCH] x86/time: update TSC stamp on restore from deep C-state
Date: Wed, 15 Jan 2020 12:32:29 +0100 [thread overview]
Message-ID: <7938484e-14a0-8edf-635b-15b05af6dace@suse.com> (raw)
In-Reply-To: <1579030581-7929-1-git-send-email-igor.druzhinin@citrix.com>
On 14.01.2020 20:36, Igor Druzhinin wrote:
> If ITSC is not available on CPU (e.g if running nested as PV shim)
> then X86_FEATURE_NONSTOP_TSC is not advertised in certain cases, i.e.
> all AMD and some old Intel processors. In which case TSC would need to
> be restored on CPU from platform time by Xen upon exiting deep C-states.
How does waking from deep C states correspond to the PV shim? I notice
that cstate_restore_tsc() gets called irrespective of the C state being
exited, so I wonder whether there's room for improvement there
independent of the issue at hand. As far as this change is concerned,
I think you want to drop the notion of "deep" from the description.
Jan
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next prev parent reply other threads:[~2020-01-15 11:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-14 19:36 [Xen-devel] [PATCH] x86/time: update TSC stamp on restore from deep C-state Igor Druzhinin
2020-01-15 9:47 ` Roger Pau Monné
2020-01-15 11:40 ` Jan Beulich
2020-01-15 11:53 ` Roger Pau Monné
2020-01-15 12:49 ` Jan Beulich
2020-01-15 13:44 ` Roger Pau Monné
2020-01-15 16:21 ` Jan Beulich
2020-01-16 9:33 ` Roger Pau Monné
2020-01-16 9:38 ` Jan Beulich
2020-01-16 12:09 ` Igor Druzhinin
2020-01-16 12:25 ` Roger Pau Monné
2020-01-15 12:25 ` Igor Druzhinin
2020-01-15 12:31 ` Igor Druzhinin
2020-01-15 12:41 ` Jan Beulich
2020-01-15 12:36 ` Igor Druzhinin
2020-01-15 13:23 ` Roger Pau Monné
2020-01-15 14:45 ` Igor Druzhinin
2020-01-15 11:32 ` Jan Beulich [this message]
2020-01-15 12:28 ` Igor Druzhinin
2020-01-15 12:39 ` Jan Beulich
2020-01-15 12:47 ` Igor Druzhinin
2020-01-15 12:54 ` Jan Beulich
2020-01-15 14:55 ` Andrew Cooper
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