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From: Tejun Heo <tj@kernel.org>
To: Lai Jiangshan <laijs@linux.alibaba.com>
Cc: linux-kernel@vger.kernel.org, Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH 4/4] workqueue: slash half memory usage in 32bit system
Date: Mon, 1 Jun 2020 11:07:23 -0400	[thread overview]
Message-ID: <20200601150723.GA31548@mtj.thefacebook.com> (raw)
In-Reply-To: <20200601084442.8284-5-laijs@linux.alibaba.com>

On Mon, Jun 01, 2020 at 08:44:42AM +0000, Lai Jiangshan wrote:
> The major memory ussage in workqueue is on the pool_workqueue.
> The pool_workqueue has alignment requirement which often leads
> to padding.
> 
> Reducing the memory usage for the pool_workqueue is valuable.
> 
> And 32bit system often has less memory, less workqueues,
> less works, less concurrent flush_workqueue()s, so we can
> slash the flush color on 32bit system to reduce memory usage
> 
> Before patch:
> The sizeof the struct pool_workqueue is 256 bytes,
> only 136 bytes is in use in 32bit system
> 
> After patch:
> The sizeof the struct pool_workqueue is 128 bytes,
> only 104 bytes is in use in 32bit system, there is still
> room for future usage.
> 
> Setting WORK_STRUCT_COLOR_BITS to 3 can't reduce the sizeof
> the struct pool_workqueue in 64bit system, unless combined
> with big refactor for unbound pwq.

Have you calculated how much memory is actually saved this way on a typical
system?

Thanks.

-- 
tejun

  reply	other threads:[~2020-06-01 15:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-01  8:44 [PATCH 0/4] workqueue: reduce the sizeof pool_workqueue Lai Jiangshan
2020-06-01  8:44 ` [PATCH 1/4] workqueue: fix a piece of comment about reserved bits for work flags Lai Jiangshan
2020-06-01  8:44 ` [PATCH 2/4] workqueue: use BUILD_BUG_ON() for compile time test instead of WARN_ON() Lai Jiangshan
2020-06-01 15:08   ` Tejun Heo
2020-06-01  8:44 ` [PATCH 3/4] workqueue: add a BUILD_BUG_ON() to check the size of struct pool_workqueue Lai Jiangshan
2020-06-01  8:44 ` [PATCH 4/4] workqueue: slash half memory usage in 32bit system Lai Jiangshan
2020-06-01 15:07   ` Tejun Heo [this message]
2020-06-02  0:08     ` Lai Jiangshan
2020-06-02 16:18       ` Tejun Heo

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