From: Valdis Kletnieks Date: Wed, 19 Apr 2006 07:23:09 +0000 (+0200) Subject: [PATCH] Document online io scheduler switching X-Git-Tag: v2.6.17-rc3~60^2~4 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=73af994c7d58dd513922dc9d5cd76b124ec02b1b;p=linux-2.6 [PATCH] Document online io scheduler switching We added the ability to change a block device's IO elevator scheduler both at kernel boot and on-the-fly, but we only documented the elevator= boot parameter. Add a quick how-to on doing it on the fly. Signed-off-by: Valdis Kletnieks Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe --- diff --git a/Documentation/block/switching-sched.txt b/Documentation/block/switching-sched.txt new file mode 100644 index 0000000000..5fa130a675 --- /dev/null +++ b/Documentation/block/switching-sched.txt @@ -0,0 +1,22 @@ +As of the Linux 2.6.10 kernel, it is now possible to change the +IO scheduler for a given block device on the fly (thus making it possible, +for instance, to set the CFQ scheduler for the system default, but +set a specific device to use the anticipatory or noop schedulers - which +can improve that device's throughput). + +To set a specific scheduler, simply do this: + +echo SCHEDNAME > /sys/block/DEV/queue/scheduler + +where SCHEDNAME is the name of a defined IO scheduler, and DEV is the +device name (hda, hdb, sga, or whatever you happen to have). + +The list of defined schedulers can be found by simply doing +a "cat /sys/block/DEV/queue/scheduler" - the list of valid names +will be displayed, with the currently selected scheduler in brackets: + +# cat /sys/block/hda/queue/scheduler +noop anticipatory deadline [cfq] +# echo anticipatory > /sys/block/hda/queue/scheduler +# cat /sys/block/hda/queue/scheduler +noop [anticipatory] deadline cfq