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| author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-04-18 19:45:00 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-07-15 09:20:27 -0300 |
| commit | 898bd37a92063e46bc8d7b870781cecd66234f92 (patch) | |
| tree | 1eac9c597d45080cc2ff366f6e882a87fcea2d2b /Documentation/block/switching-sched.rst | |
| parent | 53b9537509654a6267c3f56b4d2e7409b9089686 (diff) | |
| download | lwn-898bd37a92063e46bc8d7b870781cecd66234f92.tar.gz lwn-898bd37a92063e46bc8d7b870781cecd66234f92.zip | |
docs: block: convert to ReST
Rename the block documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/block/switching-sched.rst')
| -rw-r--r-- | Documentation/block/switching-sched.rst | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/block/switching-sched.rst b/Documentation/block/switching-sched.rst new file mode 100644 index 000000000000..42042417380e --- /dev/null +++ b/Documentation/block/switching-sched.rst @@ -0,0 +1,39 @@ +=================== +Switching Scheduler +=================== + +To choose IO schedulers at boot time, use the argument 'elevator=deadline'. +'noop' 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 + +It is possible to change the IO scheduler for a given block device on +the fly to select one of mq-deadline, none, bfq, or kyber 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/sda/queue/scheduler + [mq-deadline] kyber bfq none + # echo none >/sys/block/sda/queue/scheduler + # cat /sys/block/sda/queue/scheduler + [none] mq-deadline kyber bfq |