tree 4faf07773683ff5ec2b120d9070dbbb590199057
parent dcd989cb73ab0f7b722d64ab6516f101d9f43f88
author Tejun Heo <tj@kernel.org> 1277798834 +0200
committer Tejun Heo <tj@kernel.org> 1277798834 +0200

workqueue: implement high priority workqueue

This patch implements high priority workqueue which can be specified
with WQ_HIGHPRI flag on creation.  A high priority workqueue has the
following properties.

* A work queued to it is queued at the head of the worklist of the
  respective gcwq after other highpri works, while normal works are
  always appended at the end.

* As long as there are highpri works on gcwq->worklist,
  [__]need_more_worker() remains %true and process_one_work() wakes up
  another worker before it start executing a work.

The above two properties guarantee that works queued to high priority
workqueues are dispatched to workers and start execution as soon as
possible regardless of the state of other works.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>