>>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-de...@nongnu.org>, qemu-block@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.