From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Lin Ma <LMa@suse.com>
Cc: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] migrate_set_speed has no effect if the guest is using hugepages.
Date: Thu, 11 Jul 2019 11:24:10 +0100 [thread overview]
Message-ID: <20190711102410.GH3971@work-vm> (raw)
In-Reply-To: <BY5PR18MB3313E1E22A22D236D4C2680DC5F30@BY5PR18MB3313.namprd18.prod.outlook.com>
* Lin Ma (LMa@suse.com) wrote:
> Hi all,
Hi Lin,
> When I live migrate a qemu/kvm guest, If the guest is using huge pages, I found that
> the migrate_set_speed command had no effect during stage 2.
Can you explain what you mean by 'stage 2'?
> It was caused by commit 4c011c3 postcopy: Send whole huge pages
>
> I'm wondering that is it by design or is it a bug waiting for fix?
This is the first report I've seen for it. How did you conclude that
4c011c3 caused it? While I can see it might have some effect on the
bandwidth management, I'm surprised it has this much effect.
What size huge pages are you using - 2MB or 1GB?
I can imagine we might have a problem that since we only do the sleep
between the hugepages, if we were using 1GB hugepages then
we'd see <big chunk of data>[sleep]<big chunk of data>[sleep]
which isn't as smooth as it used to be.
Can you give me some more details of your test?
Dave
>
> Thanks,
> Lin
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2019-07-11 10:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-11 9:44 [Qemu-devel] migrate_set_speed has no effect if the guest is using hugepages Lin Ma
2019-07-11 10:24 ` Dr. David Alan Gilbert [this message]
[not found] ` <BY5PR18MB331347C441DA068E32BFDE53C5F20@BY5PR18MB3313.namprd18.prod.outlook.com>
2019-07-12 12:34 ` [Qemu-devel] 答复: " Dr. David Alan Gilbert
2019-07-15 9:43 ` [Qemu-devel] 回复: " Lin Ma
2019-08-02 10:57 ` [Qemu-devel] 回复: " Lin Ma
2019-12-05 10:31 ` 回复: 答复: [Qemu-devel] " Dr. David Alan Gilbert
[not found] ` <BY5PR18MB331333470C356200DDF0A8DAC55B0@BY5PR18MB3313.namprd18.prod.outlook.com>
2019-12-10 14:01 ` 回复: " Dr. David Alan Gilbert
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