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From: Tommi Virtanen <tv@inktank.com>
To: Vladimir Bashkirtsev <vladimir@bashkirtsev.com>
Cc: Josh Durgin <josh.durgin@inktank.com>, ceph-devel@vger.kernel.org
Subject: Re: Poor read performance in KVM
Date: Thu, 19 Jul 2012 08:52:41 -0700	[thread overview]
Message-ID: <CADvuQRGaivtgho4R=rk3c_B6eJ2GfG=tZFGNy9knoKyh2CR-zg@mail.gmail.com> (raw)
In-Reply-To: <5007FB6E.1080307@bashkirtsev.com>

On Thu, Jul 19, 2012 at 5:19 AM, Vladimir Bashkirtsev
<vladimir@bashkirtsev.com> wrote:
> Look like that osd.0 performs with low latency but osd.1 latency is way too
> high and on average it appears as 200ms. osd is backed by btrfs over LVM2.
> May be issue lie in backing fs selection? All four osds running similar

Our typical experience with btrfs right now seems to be that it works
fast when the filesystem is fresh, but as it ages, it starts to have
higher and higher delays on syncing writes. This does not seem to be
completely deterministic, that is, if you run many btrfs'es, the
symptoms start to appear at different times on different instances.

  reply	other threads:[~2012-07-19 15:53 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-15 13:13 Poor read performance in KVM Vladimir Bashkirtsev
2012-07-16  6:16 ` Josh Durgin
2012-07-18  5:46   ` Vladimir Bashkirtsev
2012-07-18 15:27     ` Josh Durgin
2012-07-19 10:46       ` Vladimir Bashkirtsev
2012-07-19 12:19       ` Vladimir Bashkirtsev
2012-07-19 15:52         ` Tommi Virtanen [this message]
2012-07-19 18:06           ` Calvin Morrow
2012-07-19 18:15             ` Mark Nelson
2012-07-20  5:24               ` Vladimir Bashkirtsev
2012-07-20  5:24             ` Vladimir Bashkirtsev
2012-07-20  5:20           ` Vladimir Bashkirtsev
     [not found]       ` <50080D9D.8010306@bashkirtsev.com>
2012-07-19 18:42         ` Josh Durgin
2012-07-20  5:31           ` Vladimir Bashkirtsev
2012-07-20 16:17           ` Vladimir Bashkirtsev
2012-07-20 16:42             ` Tommi Virtanen
2012-07-20 16:53               ` Mark Nelson
2012-07-20 16:53               ` Vladimir Bashkirtsev
2012-07-29 15:31               ` Vladimir Bashkirtsev
2012-07-29 16:13                 ` Mark Nelson
2012-07-18 15:34     ` Josh Durgin
2012-07-18  5:49   ` Vladimir Bashkirtsev
2012-07-18  5:51   ` Vladimir Bashkirtsev

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