linux/drivers/md/bcache
Michael Lyle 6e6ccc67b9 bcache: writeback: properly order backing device IO
Writeback keys are presently iterated and dispatched for writeback in
order of the logical block address on the backing device.  Multiple may
be, in parallel, read from the cache device and then written back
(especially when there are contiguous I/O).

However-- there was no guarantee with the existing code that the writes
would be issued in LBA order, as the reads from the cache device are
often re-ordered.  In turn, when writing back quickly, the backing disk
often has to seek backwards-- this slows writeback and increases
utilization.

This patch introduces an ordering mechanism that guarantees that the
original order of issue is maintained for the write portion of the I/O.
Performance for writeback is significantly improved when there are
multiple contiguous keys or high writeback rates.

Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reviewed-by: Tang Junhui <tang.junhui@zte.com.cn>
Tested-by: Tang Junhui <tang.junhui@zte.com.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-08 13:29:00 -07:00
..
alloc.c bcache: segregate flash only volume write streams 2018-01-08 13:29:00 -07:00
bcache.h bcache: writeback: properly order backing device IO 2018-01-08 13:29:00 -07:00
bset.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bset.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
btree.c bcache: Use PTR_ERR_OR_ZERO() 2018-01-08 13:29:00 -07:00
btree.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
closure.c bcache: use llist_for_each_entry_safe() in __closure_wake_up() 2017-09-27 14:54:49 -06:00
closure.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
debug.c bcache: fix wrong return value in bch_debug_init() 2018-01-08 13:29:00 -07:00
debug.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
extents.c bcache: Fix building error on MIPS 2017-11-24 16:22:58 -07:00
extents.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
io.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
journal.c bcache: Fix building error on MIPS 2017-11-24 16:22:58 -07:00
journal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig bcache: Kill dead cgroup code 2014-03-18 12:22:35 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
movinggc.c block: move bio_alloc_pages() to bcache 2018-01-06 09:18:00 -07:00
request.c bcache: ret IOERR when read meets metadata error 2018-01-08 13:29:00 -07:00
request.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stats.c md: Convert timers to use timer_setup() 2017-11-14 20:11:57 -07:00
stats.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
super.c bcache: stop writeback thread after detaching 2018-01-08 13:29:00 -07:00
sysfs.c Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
sysfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
util.c block: move bio_alloc_pages() to bcache 2018-01-06 09:18:00 -07:00
util.h block: move bio_alloc_pages() to bcache 2018-01-06 09:18:00 -07:00
writeback.c bcache: writeback: properly order backing device IO 2018-01-08 13:29:00 -07:00
writeback.h bcache: fix wrong return value in bch_debug_init() 2018-01-08 13:29:00 -07:00