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From: Paolo Bonzini <pbonzini@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Libvirt Users <libvirt-users@redhat.com>,
	Michal Privoznik <mprivozn@redhat.com>,
	Jeff Cody <jcody@redhat.com>, qemu-devel <qemu-devel@nongnu.org>,
	Joaquim Barrera <jbarrera@ac.upc.edu>
Subject: Re: [Qemu-devel] [libvirt-users] Adjust disk image migration (NBD)
Date: Mon, 24 Feb 2014 17:26:28 -0500 (EST)	[thread overview]
Message-ID: <392369891.8578031.1393280788249.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20140224151654.GB23185@stefanha-thinkpad.hitronhub.home>

> Thanks for raising this.
> 
> I noticed that mirror_run() does not throttle the first loop where it
> populates the dirty bitmap using bdrv_is_allocated_above().

This is on purpose.  Does it causes a noticeable stall in the guest?

> The main
> copy loop does take the speed limit into account but perhaps that's
> broken too.

Yeah, it looks broken.  Each iteration of the loop can write much more
than sectors_per_chunk sectors, but here:

            if (s->common.speed) {
                delay_ns = ratelimit_calculate_delay(&s->limit, sectors_per_chunk);
            } else {
                delay_ns = 0;
            }

the second argument is fixed. :/

Paolo

  reply	other threads:[~2014-02-24 22:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <52FDE495.4050004@ac.upc.edu>
2014-02-14 10:58 ` [Qemu-devel] [libvirt-users] Adjust disk image migration (NBD) Michal Privoznik
2014-02-24 15:16   ` Stefan Hajnoczi
2014-02-24 22:26     ` Paolo Bonzini [this message]
2014-02-28 10:41       ` Joaquim Barrera
2014-02-28 10:43         ` Paolo Bonzini
2014-03-11 17:13           ` Joaquim Barrera
2014-03-20  8:06             ` Stefan Hajnoczi

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