From: Peter Xu <peterx@redhat.com>
To: Artyom <starardev@gmail.com>
Cc: leobras@redhat.com, qemu-devel@nongnu.org, dgilbert@redhat.com,
quintela@redhat.com
Subject: Re: Live Migration ToDo
Date: Mon, 25 Apr 2022 19:33:57 -0400 [thread overview]
Message-ID: <Ymcv5bEhf3xe3iM0@xz-m1.local> (raw)
In-Reply-To: <CA+inuZ9rxHFXtJZFBpwFWgBRHdtfM+NHe-9y=myDDyU8W2hsig@mail.gmail.com>
On Tue, Apr 26, 2022 at 02:17:41AM +0300, Artyom wrote:
> Yes, the original postcopy paper (
> https://kartikgopalan.github.io/publications/hines09postcopy_osr.pdf)
> suggests optimizations. For example, prepaging uses hints from the VM's
> page access patterns to reduce both the number of major network faults and
> the duration of the migration phase. After examining the code in
> migration/, I could not find any mention of these optimizations. Perhaps
> the ideas from the paper have already been tried to implement in QEMU, but
> they were abandoned?
They're partly implemented, afaict.
See ram_find_and_save_block(), if we got a postcopy requested page we'll by
default remember it in rs->last_page and we'll do forward-direction-only
bubbling since we'll start to send follow up pages from there.
We also have free page reportings too with virtio-balloon device's
existance.
I don't think we have double-direction bubbling, or multi-pivot bubbling.
I'm not sure whether they were discussed/abandoned or not. I think Dave
should know the best so I'll leave the rest to him..
--
Peter Xu
prev parent reply other threads:[~2022-04-25 23:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-25 10:41 Live Migration ToDo Artyom
2022-04-25 18:34 ` Peter Xu
2022-04-25 22:39 ` Artyom
2022-04-25 22:51 ` Peter Xu
2022-04-25 23:17 ` Artyom
2022-04-25 23:33 ` Peter Xu [this message]
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