From: Stefan Richter <stefanr@s5r6.in-berlin.de>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Jens Axboe <axboe@kernel.dk>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [SCSI] sr: fix multi-drive performance, remove BKL replacement
Date: Tue, 28 Feb 2012 18:11:32 +0100 [thread overview]
Message-ID: <20120228181132.13f1088c@stein> (raw)
In-Reply-To: <1330448257.2822.138.camel@dabdike.int.hansenpartnership.com>
On Feb 28 James Bottomley wrote:
> On Tue, 2012-02-28 at 16:42 +0000, Arnd Bergmann wrote:
> > I took another look and I believe the cdi->use_count in
> > cdrom_open/cdrom_release still requires some protection that is
> > currently provided by sr_mutex.
>
> So I think this is fine ... it's protected by the bdev->bd_mutex.
>
> > Some parts of cdrom_ioctl also
> > access this variable and things like cdi->options or cdi->keeplocked.
>
> This would be problematic because we no longer lock the ioctl.
>
> > I could imagine that you can get rid of the mutex if you turn those
> > into atomics and bitops, but there may be other parts of cdrom_device_info
> > that need locking. A safer option to solve the performance problems
> > could be to replace sr_mutex with a per-device mutex inside of
> > cdrom_device_info.
>
> I'd say the latter.
Thanks Arnd and James, I will pursue this when I get the time.
--
Stefan Richter
-=====-===-- --=- ===--
http://arcgraph.de/sr/
next prev parent reply other threads:[~2012-02-28 17:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-28 14:32 [PATCH] [SCSI] sr: fix multi-drive performance, remove BKL replacement Stefan Richter
2012-02-28 15:00 ` James Bottomley
2012-02-28 16:09 ` Stefan Richter
2012-02-28 16:16 ` James Bottomley
2012-02-28 16:42 ` Arnd Bergmann
2012-02-28 16:57 ` James Bottomley
2012-02-28 17:11 ` Stefan Richter [this message]
2012-02-28 16:22 ` Stefan Richter
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=20120228181132.13f1088c@stein \
--to=stefanr@s5r6.in-berlin.de \
--cc=James.Bottomley@HansenPartnership.com \
--cc=arnd@arndb.de \
--cc=axboe@kernel.dk \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
/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.