[PATCH 0/4 V3] workqueue: avoid creating identical pwqs

[Lai Jiangshan <laijs@cn.fujitsu.com>]

Hi,

In some conditions, the default pwq or the per-node pwq might be rebuilt identically,
it causes overhead. The code of this patchset checks the attrs and avoids it.

Patch1 adds get_pwq_unlocked() due to reusing old pwq in more cases
Patch2~3 avoid to create identical pwqs
Patch4 reuse wq_update_unbound_numa_attrs_buf, simple cleanup

changed from V2:
o	get_pwq_unlocked() returns void
o	move the check of the return value of alloc_unbound_pwq() into its branch
o	wq_update_unbound_numa_attrs_buf is renamed
o	kill get_alloc_node_unbound_pwq(), may or may not replement it in future

Cc: Tejun Heo <tj@kernel.org>

Lai Jiangshan (4):
  workqueue: introduce get_pwq_unlocked()
  workqueue: reuse the current per-node pwq when its attrs are unchanged
  workqueue: reuse the current default pwq when its attrs unchanged
  workqueue: reuse wq_update_unbound_numa_attrs_buf as temporary attrs

 kernel/workqueue.c | 94 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 56 insertions(+), 38 deletions(-)

-- 
2.1.0