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From: "Maxiwell S. Garcia" <maxiwell@linux.ibm.com>
To: qemu-devel@nongnu.org
Cc: qemu-ppc@nongnu.org,
	"Maxiwell S. Garcia" <maxiwell@linux.ibm.com>,
	david@gibson.dropbear.id.au
Subject: [Qemu-devel] [PATCH 0/1] spapr: Do not re-read the clock on pre_save handler on migration
Date: Mon, 20 May 2019 17:43:39 -0300	[thread overview]
Message-ID: <20190520204340.832-1-maxiwell@linux.ibm.com> (raw)

I suggest to remove the pre_save handler that saves the timebase before
migrate. The commit that added this was ported from x86:
  6053a86fe7bd: kvmclock: reduce kvmclock difference on migration

The review [1] had a discussion about it. The author says that a VM
already paused 10 minutes ago should re-read the clock just before
migrate. But a reviewer question was not answered:

"Is it really valid to make the clock move on an already-paused
VM, only because it was migrated?"

This clock move makes the guest know about the pause between the stop
and migrate commands. Many side effects could happen after migration.

[1] http://lists.nongnu.org/archive/html/qemu-devel/2016-12/msg00610.html

Maxiwell S. Garcia (1):
  spapr: Do not re-read the clock on pre_save handler on migration

 hw/ppc/ppc.c | 24 ------------------------
 1 file changed, 24 deletions(-)

-- 
2.20.1



             reply	other threads:[~2019-05-20 20:46 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-20 20:43 Maxiwell S. Garcia [this message]
2019-05-20 20:43 ` [Qemu-devel] [PATCH 1/1] spapr: Do not re-read the clock on pre_save handler on migration Maxiwell S. Garcia
2019-05-22 23:29   ` David Gibson
2019-05-23 20:18     ` [Qemu-devel] [Qemu-ppc] " Maxiwell S. Garcia
2019-05-30  1:13       ` David Gibson
2019-06-05 19:39         ` Maxiwell S. Garcia
2019-06-12  5:14           ` David Gibson

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