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From: Jack Wang <jinpu.wang-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
To: linux-bcache-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org
Cc: dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org
Subject: bcache strange behaviour in write back mode
Date: Mon, 22 Apr 2013 21:15:14 +0200	[thread overview]
Message-ID: <51758C42.4040708@profitbricks.com> (raw)

Hi all,

We've seen strange behaviour in bcache mode in current bcache-testing
branch with Possible allocator fix:

Once I start writing data with "dd if=/dev/zero of=/dev/bcache0 bs=4k
count=10000 oflag=sync", all SSDs in the Pool go close to 100% util and
I see about 3600 writes/second in iostat for each disk in the pool, BUT
no data written in means of throughput.

Then after some seconds (the flush interval of bcache) I see the flush
of the writeback and also data written to the pool SSDs which looks
pretty much like reordering and merging happened for that data.

bcache-3.2 does not have such problem.
only bcache(master) and bcache-testing have such problem.

What's the possible reason?

Regards,
Jack

             reply	other threads:[~2013-04-22 19:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-22 19:15 Jack Wang [this message]
     [not found] ` <CAC7rs0u=epPv0c_swBSifi_fDRC0k9WpZ+34OmFdgxjR3-8WcA@mail.gmail.com>
     [not found]   ` <CAC7rs0u=epPv0c_swBSifi_fDRC0k9WpZ+34OmFdgxjR3-8WcA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-22 20:27     ` bcache strange behaviour in write back mode Jack Wang
     [not found]       ` <51759D17.5040204-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2013-04-22 21:51         ` Kent Overstreet
     [not found]           ` <20130422215138.GA9931-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2013-04-23 11:56             ` Jack Wang
     [not found]               ` <517676E7.4030805-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2013-04-23 18:40                 ` Kent Overstreet
     [not found]                   ` <CAH+dOxL9Ajsp7fruw-9nC63rJLzOqBYreeE1URxF945-pv6vug-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-24  6:56                     ` Jack Wang
     [not found] ` <51758C42.4040708-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2013-04-22 20:26   ` Kent Overstreet
2013-04-24 19:49   ` Jack Wang
     [not found]     ` <51783733.9080907-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2013-04-24 20:13       ` Kent Overstreet
     [not found]         ` <CAC7rs0s-_e1WaymU1OcuBv+Tf8hiJLED=m5Qrpxhar6Zk3H9uQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-04-24 20:29           ` Jack Wang

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