From: Juan Quintela <quintela@redhat.com>
To: Felipe Franciosi <felipe@nutanix.com>
Cc: Peter Xu <peterx@redhat.com>,
"Jason J. Herne" <jjherne@linux.vnet.ibm.com>,
amit Shah <amit.shah@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Malcolm Crossley <malcolm@nutanix.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 1/4] migration: keep bytes_xfer_prev init'd to zero
Date: Tue, 30 May 2017 18:14:10 +0200 [thread overview]
Message-ID: <87h902e2zx.fsf@secure.mitica> (raw)
In-Reply-To: <1495642203-12702-2-git-send-email-felipe@nutanix.com> (Felipe Franciosi's message of "Wed, 24 May 2017 17:10:00 +0100")
Felipe Franciosi <felipe@nutanix.com> wrote:
> The first time migration_bitmap_sync() is called, bytes_xfer_prev is set
> to ram_state.bytes_transferred which is, at this point, zero. The next
> time migration_bitmap_sync() is called, an iteration has happened and
> bytes_xfer_prev is set to 'x' bytes. Most likely, more than one second
> has passed, so the auto converge logic will be triggered and
> bytes_xfer_now will also be set to 'x' bytes.
>
> This condition is currently masked by dirty_rate_high_cnt, which will
> wait for a few iterations before throttling. It would otherwise always
> assume zero bytes have been copied and therefore throttle the guest
> (possibly) prematurely.
>
> Given bytes_xfer_prev is only used by the auto convergence logic, it
> makes sense to only set its value after a check has been made against
> bytes_xfer_now.
>
> Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
next prev parent reply other threads:[~2017-05-30 16:14 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-24 16:09 [Qemu-devel] [PATCH 0/4] migration: autoconverge counter fixes Felipe Franciosi
2017-05-24 16:10 ` [Qemu-devel] [PATCH 1/4] migration: keep bytes_xfer_prev init'd to zero Felipe Franciosi
2017-05-25 0:50 ` Peter Xu
2017-05-30 16:14 ` Juan Quintela [this message]
2017-05-24 16:10 ` [Qemu-devel] [PATCH 2/4] migration: set dirty_pages_rate before autoconverge logic Felipe Franciosi
2017-05-25 0:40 ` Peter Xu
2017-05-25 10:52 ` Felipe Franciosi
2017-05-25 11:10 ` Peter Xu
2017-05-30 16:14 ` Juan Quintela
2017-05-24 16:10 ` [Qemu-devel] [PATCH 3/4] migration: set bytes_xfer_* outside of " Felipe Franciosi
2017-05-25 0:40 ` Peter Xu
2017-05-30 16:14 ` Juan Quintela
2017-05-24 16:10 ` [Qemu-devel] [PATCH 4/4] migration: use dirty_rate_high_cnt more aggressively Felipe Franciosi
2017-05-24 16:25 ` Daniel P. Berrange
2017-05-24 16:36 ` Felipe Franciosi
2017-05-25 1:03 ` Peter Xu
2017-05-25 11:20 ` Felipe Franciosi
2017-05-26 2:45 ` Peter Xu
2017-05-30 16:17 ` Juan Quintela
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