From: Stefan Priebe <s.priebe@profihost.ag>
To: Greg Farnum <greg@inktank.com>
Cc: ceph-devel@vger.kernel.org
Subject: Re: how to debug slow rbd block device
Date: Tue, 22 May 2012 23:00:43 +0200 [thread overview]
Message-ID: <4FBBFE7B.4060406@profihost.ag> (raw)
In-Reply-To: <45F1742481D84E7A90951816DB23609F@inktank.com>
Am 22.05.2012 22:49, schrieb Greg Farnum:
> Anyway, it looks like you're just paying a synchronous write penalty
What does that exactly mean? Shouldn't one threaded write to four
260MB/s devices gives at least 100Mb/s?
> since with 1 write at a time you're getting 30-40MB/s out of rados bench, but with 16 you're getting>100MB/s.
>(If you bump up past 16 or increase the size of each with -b you may
find yourself getting even more.)
yep noticed that.
> So try enabling RBD writeback caching — see http://marc.info/?l=ceph-devel&m=133758599712768&w=2
will test tomorrow. Thanks.
Stefan
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next prev parent reply other threads:[~2012-05-22 21:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-22 12:45 how to debug slow rbd block device Stefan Priebe - Profihost AG
2012-05-22 14:52 ` Andrey Korolyov
2012-05-22 19:27 ` Stefan Priebe
2012-05-22 19:35 ` Greg Farnum
2012-05-22 19:40 ` Stefan Priebe
2012-05-22 19:52 ` Greg Farnum
2012-05-22 20:13 ` Stefan Priebe
2012-05-22 20:30 ` Stefan Priebe
2012-05-22 20:48 ` Mark Nelson
2012-05-22 20:54 ` Stefan Priebe
2012-05-22 20:49 ` Greg Farnum
2012-05-22 21:00 ` Stefan Priebe [this message]
2012-05-22 21:11 ` Greg Farnum
2012-05-23 6:18 ` Stefan Priebe - Profihost AG
2012-05-23 6:30 ` Josh Durgin
2012-05-23 7:01 ` Stefan Priebe - Profihost AG
2012-05-23 7:19 ` Josh Durgin
2012-05-23 7:22 ` Stefan Priebe - Profihost AG
2012-05-23 7:33 ` Josh Durgin
[not found] ` <CABYiri8PXT9dpCGLE7dn=_PoW8CdLxqZF87OHe=dMXEWxogb_w@mail.gmail.com>
2012-05-23 19:54 ` Josh Durgin
2012-05-23 8:20 ` Stefan Priebe - Profihost AG
2012-05-23 8:29 ` Josh Durgin
2012-05-23 7:22 ` Andrey Korolyov
2012-05-23 8:15 ` Stefan Priebe - Profihost AG
2012-05-23 11:47 ` Mark Nelson
2012-05-23 8:30 ` Stefan Priebe - Profihost AG
2012-05-23 9:10 ` Stefan Priebe - Profihost AG
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