From: Jens Axboe <jens.axboe@oracle.com>
To: Neil Brown <neilb@suse.de>
Cc: Andrew Morton <akpm@osdl.org>,
Lars Ellenberg <Lars.Ellenberg@linbit.com>,
Ingo Molnar <mingo@redhat.com>,
linux-raid@vger.kernel.org, stable@kernel.org
Subject: Re: [patch] md: pass down BIO_RW_SYNC in raid{1,10}
Date: Tue, 9 Jan 2007 08:12:25 +0100 [thread overview]
Message-ID: <20070109071224.GG11203@kernel.dk> (raw)
In-Reply-To: <17826.55504.264610.856196@notabene.brown>
On Tue, Jan 09 2007, Neil Brown wrote:
> On Monday January 8, akpm@osdl.org wrote:
> > On Mon, 8 Jan 2007 10:08:34 +0100
> > Lars Ellenberg <Lars.Ellenberg@linbit.com> wrote:
> >
> > > md raidX make_request functions strip off the BIO_RW_SYNC flag,
> > > thus introducing additional latency.
> > >
> > > fixing this in raid1 and raid10 seems to be straight forward enough.
> > >
> > > for our particular usage case in DRBD, passing this flag improved
> > > some initialization time from ~5 minutes to ~5 seconds.
> >
> > That sounds like a significant fix.
> >
> > This patch also applies to 2.6.19 and I have tagged it for a -stable
> > backport. Neil, are you OK with that?
>
> Yes, I'm OK with that, thanks.
Ack from me as well, it's really a quite nasty bug from a performance
POV. Not just for DRDB, but for io schedulers as well.
--
Jens Axboe
next prev parent reply other threads:[~2007-01-09 7:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-08 9:08 [patch] md: pass down BIO_RW_SYNC in raid{1,10} Lars Ellenberg
2007-01-08 23:02 ` Andrew Morton
2007-01-08 23:50 ` Neil Brown
2007-01-09 7:12 ` Jens Axboe [this message]
2007-01-09 14:08 ` Lars Ellenberg
2007-01-09 16:13 ` Mike Snitzer
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