>>The other block jobs (stream, backup, commit) are still using
>>a 0 ns delay and are therefore broken.
Also in mirror.c, they are block_job_sleep_ns with delay_ns, where delay_ns can
be 0.
I have seen sometime,some server/qmp hangs, on a pretty old server/slow disks.
(no more in bitmap scan with theses last patches, but on the block mirror
itself)
if (!s->synced) {
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);
if (block_job_is_cancelled(&s->common)) {
break;
}
} else if (!should_complete) {
delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0);
----- Mail original -----
De: "Stefan Hajnoczi" <stefa...@gmail.com>
À: "Fam Zheng" <f...@redhat.com>
Cc: "Kevin Wolf" <kw...@redhat.com>, "qemu-devel" <qemu-devel@nongnu.org>,
qemu-bl...@nongnu.org
Envoyé: Jeudi 9 Juillet 2015 15:02:08
Objet: Re: [Qemu-devel] [Qemu-block] [PATCH 0/3] mirror: Fix guest
responsiveness during bitmap scan
On Thu, Jul 09, 2015 at 11:47:55AM +0800, Fam Zheng wrote:
> This supersedes:
>
> http://patchwork.ozlabs.org/patch/491415/
>
> and [1] which is currently in Jeff's tree.
>
> Although [1] fixed the QMP responsiveness, Alexandre DERUMIER reported that
> guest responsiveness still suffers when we are busy in the initial dirty
> bitmap
> scanning loop of mirror job. That is because 1) we issue too many lseeks; 2)
> we
> only sleep for 0 ns which turns out quite ineffective in yielding BQL to vcpu
> threads. Both are fixed.
>
> To reproduce: start a guest, attach a 10G raw image, then mirror it. Your
> guest will immediately start to stutter (with patch [1] testing on a local
> ext4
> raw image, and "while echo -n .; do sleep 0.05; done" in guest console).
>
> This series adds block_job_relax_cpu as suggested by Stefan Hajnoczi and uses
> it in mirror job; and lets bdrv_is_allocated_above return a larger p_num as
> suggested by Paolo Bonzini (although it's done without changing the API).
>
> [1]: http://patchwork.ozlabs.org/patch/471656/ "block/mirror: Sleep
> periodically during bitmap scanning"
>
> Fam Zheng (3):
> blockjob: Introduce block_job_relax_cpu
> mirror: Use block_job_relax_cpu during bitmap scanning
> mirror: Speed up bitmap initial scanning
>
> block/mirror.c | 17 +++++++----------
> include/block/blockjob.h | 16 ++++++++++++++++
> 2 files changed, 23 insertions(+), 10 deletions(-)
This patch only converts the mirror block job to use the new relax
function. The other block jobs (stream, backup, commit) are still using
a 0 ns delay and are therefore broken. They should probably be
converted in the same series.
