[PATCH] CFQ io scheduler updates
- Adjust slice values
- Instead of one async queue, one is defined per priority level. This
prevents kernel threads (such as reiserfs/x and others) that run at
higher io priority from conflicting with others. Previously, it was a
coin toss what io prio the async queue got, it was defined by who
first set up the queue.
- Let a time slice only begin, when the previous slice is completely
done. Previously we could be somewhat unfair to a new sync slice, if
the previous slice was async and had several ios queued. This might
need a little tweaking if throughput suffers a little due to this,
allowing perhaps an overlap of a single request or so.
- Optimize the calling of kblockd_schedule_work() by doing it only when
it is strictly necessary (no requests in driver and work left to do).
- Correct sync vs async logic. A 'normal' process can be purely async as
well, and a flusher can be purely sync as well. Sync or async is now a
property of the class defined and requests pending. Previously writers
could be considered sync, when they were really async.
- Get rid of the bit fields in cfqq and crq, use flags instead.
- Various other cleanups and fixes
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index 7811300..8a453a0 100644
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -12,6 +12,7 @@
#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
+#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)