All of lore.kernel.org
 help / color / mirror / Atom feed
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190520204340.832-1-maxiwell@linux.ibm.com \
    --to=maxiwell@linux.ibm.com \
    --cc=david@gibson.dropbear.id.au \
    --cc=qemu-devel@nongnu.org \
    --cc=qemu-ppc@nongnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.