| commit | 51a858817dcdbbdee22cb54b0b2b26eb145ca5b6 | [log] [tgz] |
|---|---|---|
| author | Merlijn Wajer <merlijn@archive.org> | Tue Feb 18 15:39:17 2020 +0100 |
| committer | Martin K. Petersen <martin.petersen@oracle.com> | Mon Feb 24 15:01:57 2020 -0500 |
| tree | 2ca71f96adf0db09c1a7f184fe6f17a8cfb9d367 | |
| parent | 679b2ec8e060ca7a90441aff5e7d384720a41b76 [diff] |
scsi: sr: get rid of sr global mutex
When replacing the Big Kernel Lock in commit 2a48fc0ab242 ("block:
autoconvert trivial BKL users to private mutex"), the lock was replaced
with a sr-wide lock.
This causes very poor performance when using multiple sr devices, as the sr
driver was not able to execute more than one command to one drive at any
given time, even when there were many CD drives available.
Replace the global mutex with per-sr-device mutex.
Someone tried this patch at the time, but it never made it upstream, due to
possible concerns with race conditions, but it's not clear the patch
actually caused those:
https://www.spinics.net/lists/linux-scsi/msg63706.html
https://www.spinics.net/lists/linux-scsi/msg63750.html
Also see
http://lists.xiph.org/pipermail/paranoia/2019-December/001647.html
Link: https://lore.kernel.org/r/20200218143918.30267-1-merlijn@archive.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Merlijn Wajer <merlijn@archive.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>