From 23c76983e23628c7762137a00651e3e371aa97d3 Mon Sep 17 00:00:00 2001 From: "Alan D. Brunelle" Date: Mon, 15 Oct 2007 13:22:26 +0200 Subject: Some IO scheduler cleanup in Documentation/block as-iosched.txt: o Changed IO scheduler selection text to a reference to the switching-sched.txt file. o Fixed typo: 'for up time...' -> 'for up to...' o Added short description of the est_time file. deadline-iosched.txt: o Changed IO scheduler selection text to a reference to the switching-sched.txt file. o Removed references to non-existent seek-cost and stream_unit. o Fixed typo: 'write_starved' -> 'writes_starved' switching-sched.txt: o Added in boot-time argument to set the default IO scheduler. (From as-iosched.txt) o Added in sysfs mount instructions. (From deadline-iosched.txt) Signed-off-by: Alan D. Brunelle Signed-off-by: Jens Axboe --- Documentation/block/switching-sched.txt | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'Documentation/block/switching-sched.txt') diff --git a/Documentation/block/switching-sched.txt b/Documentation/block/switching-sched.txt index 5fa130a6753..634c952e196 100644 --- a/Documentation/block/switching-sched.txt +++ b/Documentation/block/switching-sched.txt @@ -1,3 +1,18 @@ +To choose IO schedulers at boot time, use the argument 'elevator=deadline'. +'noop', 'as' and 'cfq' (the default) are also available. IO schedulers are +assigned globally at boot time only presently. + +Each io queue has a set of io scheduler tunables associated with it. These +tunables control how the io scheduler works. You can find these entries +in: + +/sys/block//queue/iosched + +assuming that you have sysfs mounted on /sys. If you don't have sysfs mounted, +you can do so by typing: + +# mount none /sys -t sysfs + 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 @@ -20,3 +35,9 @@ noop anticipatory deadline [cfq] # echo anticipatory > /sys/block/hda/queue/scheduler # cat /sys/block/hda/queue/scheduler noop [anticipatory] deadline cfq + +Each io queue has a set of io scheduler tunables associated with it. These +tunables control how the io scheduler works. You can find these entries +in: + +/sys/block//queue/iosched -- cgit v1.2.3