linux-kernel - Re: [PATCH] mm: thp: remove use_zero

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Message-ID: <20180722035156.GA12125@bombadil.infradead.org>
Date:   Sat, 21 Jul 2018 20:51:56 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Yang Shi <yang.shi@...ux.alibaba.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kirill@...temov.name, hughd@...gle.com, aaron.lu@...el.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: thp: remove use_zero_page sysfs knob

On Fri, Jul 20, 2018 at 02:05:52PM -0700, David Rientjes wrote:
> The huge zero page can be reclaimed under memory pressure and, if it is, 
> it is attempted to be allocted again with gfp flags that attempt memory 
> compaction that can become expensive.  If we are constantly under memory 
> pressure, it gets freed and reallocated millions of times always trying to 
> compact memory both directly and by kicking kcompactd in the background.
> 
> It likely should also be per node.

Have you benchmarked making the non-huge zero page per-node?