Commit Graph

8 Commits

Author SHA1 Message Date
Christoph Hellwig
a2b809672e block: replace REQ_NOIDLE with REQ_IDLE
Noidle should be the default for writes as seen by all the compounds
definitions in fs.h using it.  In fact only direct I/O really should
be using NODILE, so turn the whole flag around to get the defaults
right, which will make our life much easier especially onces the
WRITE_* defines go away.

This assumes all the existing "raw" users of REQ_SYNC for writes
want noidle behavior, which seems to be spot on from a quick audit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
2016-11-01 09:43:26 -06:00
Libor Pechacek
bcebb4cc20 Fix CFQ I/O scheduler parameter name in documentation
As seen in block/cfq-iosched.c, the parameter name is low_latency.

Signed-off-by: Libor Pechacek <lpechacek@suse.cz>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2015-12-10 11:26:24 -07:00
Masanari Iida
c9f3f2d8b3 doc: Fix typo in doucmentations
Correct typo (double words) in documentations.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2013-07-25 12:34:15 +02:00
Namjae Jeon
fdc6fdc52e Documentation: cfq-iosched: update documentation help for cfq tunables
Add the documentation text for latency, target_latency & group_idle
tunnable parameters in the block/cfq-iosched.txt.
Also fix few typo(spelling) mistakes.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>

Language somewhat modified by Jens.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-04-09 14:57:06 +02:00
Tejun Heo
d02f7aa8dc cfq-iosched: enable full blkcg hierarchy support
With the previous two patches, all cfqg scheduling decisions are based
on vfraction and ready for hierarchy support.  The only thing which
keeps the behavior flat is cfqg_flat_parent() which makes vfraction
calculation consider all non-root cfqgs children of the root cfqg.

Replace it with cfqg_parent() which returns the real parent.  This
enables full blkcg hierarchy support for cfq-iosched.  For example,
consider the following hierarchy.

        root
      /      \
   A:500      B:250
  /     \
 AA:500  AB:1000

For simplicity, let's say all the leaf nodes have active tasks and are
on service tree.  For each leaf node, vfraction would be

 AA: (500  / 1500) * (500 / 750) =~ 0.2222
 AB: (1000 / 1500) * (500 / 750) =~ 0.4444
  B:                 (250 / 750) =~ 0.3333

and vdisktime will be distributed accordingly.  For more detail,
please refer to Documentation/block/cfq-iosched.txt.

v2: cfq-iosched.txt updated to describe group scheduling as suggested
    by Vivek.

v3: blkio-controller.txt updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2013-01-09 08:05:11 -08:00
Namjae Jeon
2792d87193 Documentation: update tunable options in block/cfq-iosched.txt
Update tunable options in block/cfq-iosched.txt.

Signed-off-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-08-09 15:27:29 +02:00
Vivek Goyal
4931402a9d cfq-iosched: Add documentation about idling
There are always questions about why CFQ is idling on various conditions.
Recent ones is Christoph asking again why to idle on REQ_NOIDLE. His
assertion is that XFS is relying more and more on workqueues and is
concerned that CFQ idling on IO from every workqueue will impact
XFS badly.

So he suggested that I add some more documentation about CFQ idling
and that can provide more clarity on the topic and also gives an
opprotunity to poke a hole in theory and lead to improvements.

So here is my attempt at that. Any comments are welcome.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-08-05 09:42:20 +02:00
Vivek Goyal
6d6ac1c1a3 cfq-iosched: Documentation help for new tunables
Some documentation to provide help with tunables.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-08-23 12:25:29 +02:00