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authorAlan D. Brunelle <Alan.Brunelle@hp.com>2007-10-15 15:22:26 +0400
committerJens Axboe <jens.axboe@oracle.com>2007-10-16 11:59:55 +0400
commit23c76983e23628c7762137a00651e3e371aa97d3 (patch)
tree3e335f0eb806b7890542420d6c2f635823d210ff /Documentation/block/switching-sched.txt
parent26bbb29a2a4e1491238ae49bf3294955dc0ab662 (diff)
downloadlinux-23c76983e23628c7762137a00651e3e371aa97d3.tar.xz
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 <Alan.Brunelle@hp.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'Documentation/block/switching-sched.txt')
-rw-r--r--Documentation/block/switching-sched.txt21
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/block/switching-sched.txt b/Documentation/block/switching-sched.txt
index 5fa130a67531..634c952e1964 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/<device>/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/<device>/queue/iosched