From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Tejun Heo <tj@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] workqueue: add __WQ_FREEZING and remove POOL_FREEZING
Date: Thu, 17 Apr 2014 07:58:55 +0800 [thread overview]
Message-ID: <534F193F.2070600@cn.fujitsu.com> (raw)
In-Reply-To: <20140416195109.GD22569@htj.dyndns.org>
On 04/17/2014 03:51 AM, Tejun Heo wrote:
> Hello,
>
> On Tue, Mar 25, 2014 at 05:56:04PM +0800, Lai Jiangshan wrote:
>> freezing is nothing related to pools, but POOL_FREEZING adds a connection,
>> and causes freeze_workqueues_begin() and thaw_workqueues() complicated.
>>
>> Since freezing is workqueue instance attribute, so we introduce __WQ_FREEZING
>> to wq->flags instead and remove POOL_FREEZING.
>>
>> we set __WQ_FREEZING only when freezable(to simplify pwq_adjust_max_active()),
>> make freeze_workqueues_begin() and thaw_workqueues() fast skip non-freezable wq.
>
> Please wrap the description to 80 columns.
>
>> @@ -3730,18 +3726,13 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
>> static void pwq_adjust_max_active(struct pool_workqueue *pwq)
>> {
>> struct workqueue_struct *wq = pwq->wq;
>> - bool freezable = wq->flags & WQ_FREEZABLE;
>>
>> - /* for @wq->saved_max_active */
>> + /* for @wq->saved_max_active and @wq->flags */
>> lockdep_assert_held(&wq->mutex);
>>
>> - /* fast exit for non-freezable wqs */
>> - if (!freezable && pwq->max_active == wq->saved_max_active)
>> - return;
>> -
>
> Why are we removing the above? Can't we still test __WQ_FREEZING as
> we're holding wq->mutex? I don't really mind removing the
> optimization but the patch description at least has to explain what's
> going on.
This part was in other old patch: https://lkml.org/lkml/2013/4/3/756
I admit the changelogs(old patch&this) are bad.
But I still consider it would be better if we split it to two patches:
(https://lkml.org/lkml/2013/4/3/748 & https://lkml.org/lkml/2013/4/3/756)
There are different aims in the patches.
Any thinks? And sorry for I didn't keep to push the patches at that time.
Thanks
Lai
>
> ...
>> list_for_each_entry(wq, &workqueues, list) {
>> + if (!(wq->flags & WQ_FREEZABLE))
>> + continue;
>
> Ah, okay, you're not calling the function at all if WQ_FREEZABLE is
> not set. I couldn't really understand what you were trying to say in
> the patch description. Can you please try to refine the description
> more? It's better to be verbose and clear than short and difficult to
> understand.
>
> Thanks.
>
next prev parent reply other threads:[~2014-04-16 23:55 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 2:05 [PATCH 1/7] workqueue: add __WQ_FREEZING and remove POOL_FREEZING Lai Jiangshan
2013-04-04 2:05 ` [PATCH 2/7] workqueue: set __WQ_FREEZING only when freezable Lai Jiangshan
2013-04-04 2:05 ` [PATCH 3/7] workqueue: rename rebind_workers() to associate_cpu_pool() Lai Jiangshan
2013-04-04 14:15 ` Tejun Heo
2013-04-04 2:05 ` [PATCH 4/7] workqueue: simplify workqueue_cpu_up_callback(CPU_ONLINE) Lai Jiangshan
2013-04-04 2:05 ` [PATCH 5/7] workqueue, use default pwq when fail to allocate node pwd Lai Jiangshan
2013-04-04 14:34 ` Tejun Heo
2013-04-04 2:05 ` [PATCH 6/7] workqueue: node-awared allocation for unbound pool Lai Jiangshan
2013-04-04 14:38 ` Tejun Heo
2013-04-04 2:05 ` [PATCH 7/7] workqueue: avoid false negative WARN_ON() Lai Jiangshan
2013-04-04 14:55 ` [PATCH] workqueue: avoid false negative WARN_ON() in destroy_workqueue() Tejun Heo
2013-04-05 7:39 ` Lai Jiangshan
2013-04-04 14:12 ` [PATCH 1/7] workqueue: add __WQ_FREEZING and remove POOL_FREEZING Tejun Heo
2013-04-20 16:12 ` Lai Jiangshan
2013-04-21 1:29 ` Tejun Heo
2014-03-25 9:56 ` [PATCH] " Lai Jiangshan
2014-03-27 12:08 ` Lai Jiangshan
2014-03-27 14:48 ` Tejun Heo
2014-04-16 19:51 ` Tejun Heo
2014-04-16 23:58 ` Lai Jiangshan [this message]
2014-04-17 15:29 ` Tejun Heo
2014-04-16 20:50 ` Tejun Heo
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