From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Alex Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] migration: broken ram_save_pending
Date: Tue, 04 Feb 2014 13:07:44 +0100 [thread overview]
Message-ID: <52F0D810.4070806@redhat.com> (raw)
In-Reply-To: <52F0D611.7070105@ozlabs.ru>
Il 04/02/2014 12:59, Alexey Kardashevskiy ha scritto:
>> > With the default throttling of 32 MiB/s, bandwidth must be something like
>> > 33000 (expressed in bytes/ms) with the default settings, and then max_size
>> > should be 33000*3*10^9 / 10^6 = 6000000. Where is my computation wrong?
>
> migrate_max_downtime() = 30000000 = 3*10^7.
Oops, that's the mistake.
> When the migration is in iterating stage, bandwidth is a speed in last
> 100ms which is usually 5 blocks 250KB each so it is
> 1250000/100=12500bytes/s and max_size=12500*30000000/10^6=375000 which is
> less than the last chunk is.
>
>
Perhaps our default maximum downtime is too low. 30 ms doesn't seem
achievable in practice with 32 MiB/s bandwidth. Just making it 300 ms
or so should fix your problem.
Paolo
next prev parent reply other threads:[~2014-02-04 12:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 7:15 [Qemu-devel] migration: broken ram_save_pending Alexey Kardashevskiy
2014-02-04 10:46 ` Paolo Bonzini
2014-02-04 11:59 ` Alexey Kardashevskiy
2014-02-04 12:07 ` Paolo Bonzini [this message]
2014-02-04 12:16 ` Alexey Kardashevskiy
2014-02-04 14:00 ` Paolo Bonzini
2014-02-04 22:17 ` Alexey Kardashevskiy
2014-02-05 7:18 ` Paolo Bonzini
2014-02-05 9:09 ` Dr. David Alan Gilbert
2014-02-05 16:35 ` Paolo Bonzini
2014-02-05 16:42 ` Dr. David Alan Gilbert
2014-02-05 16:45 ` Paolo Bonzini
2014-02-06 3:10 ` Alexey Kardashevskiy
2014-02-06 11:24 ` Dr. David Alan Gilbert
2014-02-07 5:39 ` Alexey Kardashevskiy
2014-02-07 8:55 ` Dr. David Alan Gilbert
2014-02-06 23:49 ` Paolo Bonzini
2014-02-07 5:42 ` Alexey Kardashevskiy
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