linux-kernel - Re: [PATCH v2 0/5] mm: support parallel free of memory

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Date:   Thu, 16 Mar 2017 15:34:03 +0800
From:   Aaron Lu <aaron.lu@...el.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...el.com>,
        Tim Chen <tim.c.chen@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ying Huang <ying.huang@...el.com>
Subject: Re: [PATCH v2 0/5] mm: support parallel free of memory

On Wed, Mar 15, 2017 at 05:28:43PM +0100, Michal Hocko wrote:
... ...
> After all the amount of the work to be done is the same we just risk
> more lock contentions, unexpected CPU usage etc.

I start to realize this is a good question.

I guess max_active=4 produced almost the best result(max_active=8 is
only slightly better) is due to the test box is a 4 node machine and
therefore, there are 4 zone->lock to contend(let's ignore those tiny
zones only available in node 0).

I'm going to test on a EP to see if max_active=2 will suffice to produce
a good enough result. If so, the proper default number should be the
number of nodes.

Thanks.