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Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes b
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward |
Date: |
Wed, 7 May 2014 20:23:27 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, May 06, 2014 at 09:54:35PM +0200, Marcin Gibuła wrote:
> >Yes, and it isn't. Any ideas why it's not? This patch really just uses
> >the guest visible kvmclock time rather than the host view of it on
> >migration.
> >
> >There is definitely something very broken on the host's side since it
> >does return a smaller time than the guest exposed interface indicates.
>
> Don't know if helps but here are example values from
> time_at_migration and s->clock from your patch.
>
> Tested on 5 restores of saved VM that (used to) hang:
>
> s->clock time_at_migration
> 157082235125698 157113284546655
> 157082235125698 157113298196976
> 157082235125698 157113284615117
> 157082235125698 157113284486601
> 157082235125698 157113284479740
>
> Now, when I compare system time on guest with and without patch:
>
> On unpatched qemu vm restores with date: Apr 18 06:56:36
> On patched qemu it says: Apr 18 06:57:06
>
> --
> mg
Marcin,
Can you turn off the TSC clock on the host and attempt to reproduce the
issue, without Alexander's patch?
Just
echo hpet > /sys/devices/system/clocksource/clocksource0/current_clocksource
(or any other clock except tsc if you don't have hpet).
TIA.
Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward, Marcelo Tosatti, 2014/05/05
Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward, Alexander Graf, 2014/05/06
Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward, Marcelo Tosatti, 2014/05/07