linux-kernel - Re: [PATCH 0/7 V2] workqueue: cleanup for attr management

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Message-ID: <555934B9.7030907@cn.fujitsu.com>
Date:	Mon, 18 May 2015 08:39:21 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 0/7 V2] workqueue: cleanup for attr management

ping

On 05/12/2015 08:32 PM, Lai Jiangshan wrote:
> Hi,
> 
> This is the V2 version of the V1 pathset.  But it is just the updated
> version of the patch1&2 of the V1 patchset.
> 
> [1/5 V1] is split into [1/7 V2] and [2/7 V2].
> [2/5 V1] is split into [3,4,5,6,7/7 V2].
> 
> [1/7] extends the wq_pool_mutex lock region in the apply_workqueue_attrs().
> 	It is a basic patch for all the later patches except the [6/7 V2].
> [2/7] simplifies wq_update_unbound_numa() since lock requirement is eased.
> 
> [3/7] introduces get_pwq_unlocked() for reusing existing pwqs
> 	It is also a basic patch for all the later patches except the [6/7 V2].
> [4,5,6/7] apply the good code of wq_update_unbound_numa() to
> 	     apply_workqueue_attrs(): reuse the unchanged per-node/default pwq
> 	     and reuse the preallocated wq_update_unbound_numa_attrs_buf.
> 
> [2,3,4,5,6/7] try to make the per-node allocation are the same in
> 	wq_update_unbound_numa() and apply_workqueue_attrs(), but they
> 	are not exactly the same. wq_update_unbound_numa() directly returns
> 	when the pwq unchanged.
> 
> [7/7] adds get_node_unbound_pwq() which uses the per-node allocation
> 	behavior of the apply_workqueue_attrs().  So wq_update_unbound_numa()
> 	has some overhead introduced.  But cpu-hotplug path is cold path,
> 	it is Ok.
> 
> 	It removes some comments without adding the corresponding ones back.
> 
> Other changed from V1:
> 	The unneeded comment about the stableness of the wq->unbound_attrs
> 	is removed in [2/7].
> 
> 	alloc_node_unbound_pwq() is renamed to get_node_unbound_pwq().
> 	@use_dfl_when_fail is removed from get_node_unbound_pwq().
> 	get_node_unbound_pwq() is shorter under the help of get_pwq_unlocked().
> 
> 	apply_wqattrs_cleanup() is not protected by wq_pool_mutex
> 
> 	some comment revised as TJ's suguested.
> 
> Thanks,
> Lai
> 
> Cc: Tejun Heo <tj@...nel.org>
> 
> Lai Jiangshan (7):
>   workqueue: wq_pool_mutex protects the attrs-installation
>   workqueue: simplify wq_update_unbound_numa()
>   workqueue: introduce get_pwq_unlocked()
>   workqueue: reuse the current per-node pwq when its attrs unchanged
>   workqueue: reuse the current default pwq when its attrs unchanged
>   workqueue: reuse wq_update_unbound_numa_attrs_buf as temporary attrs
>   workqueue: add get_node_unbound_pwq()
> 
>  kernel/workqueue.c | 197 ++++++++++++++++++++++++++---------------------------
>  1 file changed, 95 insertions(+), 102 deletions(-)
> 

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