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Re: [Qemu-devel] ?????? ?????? ?????? ?????? ?? ???? ?????? qemu vm big


From: Josh Durgin
Subject: Re: [Qemu-devel] ?????? ?????? ?????? ?????? ?? ???? ?????? qemu vm big network latency when met heavy io
Date: Thu, 16 Jan 2014 22:57:29 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0

On 01/15/2014 10:12 PM, ?????? wrote:
Hi Josh

# strings /usr/bin/qemu-system-x86_64 | grep rbd_aio
rbd_aio_write
rbd_aio_flush
rbd_aio_read
rbd_aio_create_completion
rbd_aio_release
rbd_aio_discard
rbd_aio_get_return_value

So, librbd's asynchronous flush is being used.

I set log settings, fetch the log and ping log with timestamped, all
logs are in the attachment.

Excellent, thanks.

It seems that I doesn't have permission to generate a new issue
on tracker.ceph.com, when I click the 'Register' it show a 'internal
error' page.

Seems to be working for me. In any case, I created
http://tracker.ceph.com/issues/7165 to track the problem.

Looking through the logs, it may have been already solved in
a couple commits after 0.67.5. Namely, the cache was starting the flush
of too much dirty data at once while holding a lock, preventing other
I/O from the guest from starting, and thus blocking the qemu thread
handling the I/O.

I added the relevant commits to the wip-objectcacher-flusher-dumpling
branch in ceph.git. Could you install librbd from that branch and see
if it fixes the problem? Instructions for getting these packages are:

http://ceph.com/docs/master/install/get-packages/#add-ceph-development

Thanks,
Josh




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