Subject: Re: [PATCH v2 3/5] mm: use a dedicated workqueue for the free workers
To: Aaron Lu <aaron.lu@intel.com>, Minchan Kim <minchan@kernel.org>
References: <1489568404-7817-1-git-send-email-aaron.lu@intel.com>
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 <20170322063335.GF30149@bbox> <20170322084103.GC2360@aaronlu.sh.intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Tim Chen <tim.c.chen@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Ying Huang <ying.huang@intel.com>
From: Dave Hansen <dave.hansen@intel.com>
Message-ID: <4549498a-befc-133d-b204-dd69b191e579@intel.com>
Date: Thu, 23 Mar 2017 08:38:43 -0700
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On 03/22/2017 01:41 AM, Aaron Lu wrote:
> On Wed, Mar 22, 2017 at 03:33:35PM +0900, Minchan Kim wrote:
>> On Wed, Mar 15, 2017 at 05:00:02PM +0800, Aaron Lu wrote:
>>> Introduce a workqueue for all the free workers so that user can fine
>>> tune how many workers can be active through sysfs interface: max_active.
>>> More workers will normally lead to better performance, but too many can
>>> cause severe lock contention.
>>
>> Let me ask a question.
>>
>> How well can workqueue distribute the jobs in multiple CPU?
> 
> I would say it's good enough for my needs.
> After all, it doesn't need many kworkers to achieve the 50% time
> decrease: 2-4 kworkers for EP and 4-8 kworkers for EX are enough from
> previous attched data.

It's also worth noting that we'd like to *also* like to look into
increasing how scalable freeing pages to a given zone is.