From: Alasdair G Kergon <agk@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Brian Wood <brian.j.wood@intel.com>,
Daniel Walker <dwalker@mvista.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Jonathan Brassow <jbrassow@redhat.com>,
Jun'ichi Nomura <j-nomura@ce.jp.nec.com>,
Milan Broz <mbroz@redhat.com>, Paul Jimenez <pj@place.org>,
"Robert P. J. Day" <rpjday@crashcourse.ca>,
Vasily Averin <vvs@sw.ru>,
dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [git pull] device-mapper update for 2.6.25
Date: Fri, 8 Feb 2008 03:24:23 +0000 [thread overview]
Message-ID: <20080208032423.GX8075@agk.fab.redhat.com> (raw)
In-Reply-To: <20080207190447.b4dcfe0c.akpm@linux-foundation.org>
On Thu, Feb 07, 2008 at 07:04:47PM -0800, Andrew Morton wrote:
> On Fri, 8 Feb 2008 02:45:32 +0000 Alasdair G Kergon <agk@redhat.com> wrote:
>
> > dm: move deferred bio flushing to workqueue
>
> To my unpracticed eye this one looks fairly fundamental. Unfortunately the
> changelog:
>
> Add a single-thread workqueue for each mapped device and move flushing
> of the lists of pushback and deferred bios to this new workqueue.
>
> tells us nothing of the reasons for this change. (It should have done so!)
>
> It _looks_ pretty unscalable. Perhaps these deferred BIOs don't happen
> very often?
Indeed - it's a rare occurrence - happens when the dm device is
suspended/resumed which usually means it was being reconfigured by something in
userspace.
It's the first patch of a series that will provide barrier support (slated for
2.6.26).
The appearance of all these workqueues in dm goes back to this old change:
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
Alasdair
--
agk@redhat.com
prev parent reply other threads:[~2008-02-08 3:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-08 2:45 [git pull] device-mapper update for 2.6.25 Alasdair G Kergon
2008-02-08 3:04 ` Andrew Morton
2008-02-08 3:04 ` Andrew Morton
2008-02-08 3:24 ` Alasdair G Kergon [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20080208032423.GX8075@agk.fab.redhat.com \
--to=agk@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=brian.j.wood@intel.com \
--cc=dm-devel@redhat.com \
--cc=dwalker@mvista.com \
--cc=herbert@gondor.apana.org.au \
--cc=j-nomura@ce.jp.nec.com \
--cc=jbrassow@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mbroz@redhat.com \
--cc=pj@place.org \
--cc=rpjday@crashcourse.ca \
--cc=torvalds@linux-foundation.org \
--cc=vvs@sw.ru \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.