From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Singh, Balbir" <sblbir@amazon.com>,
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Subject: Re: [RFC PATCH V2 11/11] x86: tsc: avoid system instability in hibernation
Date: Mon, 13 Jan 2020 22:50:59 +0100 [thread overview]
Message-ID: <CAJZ5v0jv+5aLY3N4wFSitu61o9S8tJWEWGGn1Xyw-P82_TwFdQ@mail.gmail.com> (raw)
In-Reply-To: <20200113124247.GG2827@hirez.programming.kicks-ass.net>
On Mon, Jan 13, 2020 at 1:43 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Mon, Jan 13, 2020 at 11:43:18AM +0000, Singh, Balbir wrote:
> > For your original comment, just wanted to clarify the following:
> >
> > 1. After hibernation, the machine can be resumed on a different but compatible
> > host (these are VM images hibernated)
> > 2. This means the clock between host1 and host2 can/will be different
> >
> > In your comments are you making the assumption that the host(s) is/are the
> > same? Just checking the assumptions being made and being on the same page with
> > them.
>
> I would expect this to be the same problem we have as regular suspend,
> after power off the TSC will have been reset, so resume will have to
> somehow bridge that gap. I've no idea if/how it does that.
In general, this is done by timekeeping_resume() and the only special
thing done for the TSC appears to be the tsc_verify_tsc_adjust(true)
call in tsc_resume().
> I remember some BIOSes had crazy TSC ideas for suspend2ram, and we grew
> tsc_restore_sched_clock_state() for it.
>
> Playing crazy games like what you're doing just isn't it though.
Right.
next prev parent reply other threads:[~2020-01-13 21:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 23:45 [RFC PATCH V2 11/11] x86: tsc: avoid system instability in hibernation Anchal Agarwal
2020-01-08 10:50 ` Peter Zijlstra
2020-01-10 15:35 ` Eduardo Valentin
2020-01-13 10:16 ` Peter Zijlstra
2020-01-13 11:43 ` Singh, Balbir
2020-01-13 11:48 ` Rafael J. Wysocki
2020-01-13 12:42 ` Peter Zijlstra
2020-01-13 21:50 ` Rafael J. Wysocki [this message]
2020-01-13 23:30 ` Rafael J. Wysocki
2020-01-14 19:29 ` Anchal Agarwal
2020-01-22 20:07 ` Anchal Agarwal
2020-01-23 16:27 ` Boris Ostrovsky
2020-01-13 13:01 ` [Xen-devel] " Andrew Cooper
2020-01-13 13:54 ` David Woodhouse
2020-01-13 15:02 ` Singh, Balbir
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