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linux/block
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Alan D. Brunelle ac9fafa124 block: Skip I/O merges when disabled 
The block I/O + elevator + I/O scheduler code spend a lot of time trying
to merge I/Os -- rightfully so under "normal" circumstances. However,
if one were to know that the incoming I/O stream was /very/ random in
nature, the cycles are wasted.

This patch adds a per-request_queue tunable that (when set) disables
merge attempts (beyond the simple one-hit cache check), thus freeing up
a non-trivial amount of CPU cycles.

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-04-29 14:48:55 +02:00
..
as-iosched.c block: kill swap_io_context() 2008-02-01 11:34:49 +01:00
blk-barrier.c block: rename and export rq_init() 2008-04-29 14:48:55 +02:00
blk-core.c block: add large command support 2008-04-29 14:48:55 +02:00
blk-exec.c block: make core bits checkpatch compliant 2008-02-01 09:26:33 +01:00
blk-ioc.c cfq-iosched: add hlist for browsing parallel to the radix tree 2008-02-19 10:04:00 +01:00
blk-map.c block: add dma alignment and padding support to blk_rq_map_kern 2008-04-29 09:50:34 +02:00
blk-merge.c block: make queue flags non-atomic 2008-04-29 14:48:33 +02:00
blk-settings.c block: make queue flags non-atomic 2008-04-29 14:48:33 +02:00
blk-sysfs.c block: Skip I/O merges when disabled 2008-04-29 14:48:55 +02:00
blk-tag.c block: make queue flags non-atomic 2008-04-29 14:48:33 +02:00
blk.h block: rename and export rq_init() 2008-04-29 14:48:55 +02:00
blktrace.c blktrace: Add blktrace ioctls to SCSI generic devices 2008-01-28 10:04:46 +01:00
bsg.c [SCSI] bsg: add release callback support 2008-04-22 15:16:32 -05:00
cfq-iosched.c cfq-iosched: do not leak ioc_data across iosched switches 2008-04-10 08:28:01 +02:00
compat_ioctl.c ide: remove broken/dangerous HDIO_[UNREGISTER,SCAN]_HWIF ioctls (take 3) 2008-04-18 00:46:24 +02:00
deadline-iosched.c block: let elv_register() return void 2007-12-18 08:29:28 +01:00
elevator.c block: Skip I/O merges when disabled 2008-04-29 14:48:55 +02:00
genhd.c genhd must_check warning fix 2008-03-12 12:34:37 -07:00
ioctl.c compat_ioctl: move common block ioctls to compat_blkdev_ioctl 2007-10-10 09:26:00 +02:00
Kconfig Kconfig: clean up block/Kconfig help descriptions 2008-04-21 09:51:04 +02:00
Kconfig.iosched update I/O sched Kconfig help texts - CFQ is now default, not AS. 2007-02-17 20:08:22 +01:00
Makefile block: ll_rw_blk.c split, add blk-merge.c 2008-01-29 21:55:12 +01:00
noop-iosched.c block: let elv_register() return void 2007-12-18 08:29:28 +01:00
scsi_ioctl.c block: no need to initialize rq->cmd with blk_get_request 2008-04-29 14:48:55 +02:00