On Sun, 26 Mar 2006 22:19:52 PST, "Randy.Dunlap" said: > Patches accepted... Please summarize what you have found, even if not in > patch format (and I'll make it a patch). From: Valdis Kletnieks <[email protected]> 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 <[email protected]> --- --- linux-2.6.16-mm1/Documentation/block/switching-sched.txt.new 2006-03-27 03:26:25.000000000 -0500 +++ linux-2.6.16-mm1/Documentation/block/switching-sched.txt 2006-03-27 03:33:39.000000000 -0500 @@ -0,0 +1,22 @@ +As of the Linux 2.6.mumble 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
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