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Date: Wed, 25 Apr 2018 14:13:03 -0500 (CDT)
From: Christopher Lameter <cl@linux.com>
Subject: Re: [RFC] Scale slub page allocations with memory size
In-Reply-To: <20180425044752.GB15974@bombadil.infradead.org>
Message-ID: <alpine.DEB.2.20.1804251410100.31137@nuc-kabylake>
References: <20180425044752.GB15974@bombadil.infradead.org>
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To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org

On Tue, 24 Apr 2018, Matthew Wilcox wrote:

> From: Matthew Wilcox <mawilcox@microsoft.com>
>
> With larger memory sizes, it's more important to avoid external
> fragmentation than reduce memory usage.

If you do that then the higher order pages that we will then be using will
be exhausted faster. I think we need a generic fix to be able to preserve
higher order pages first.

Dave Hansen and I thought about a 2M basepage configuration?

Something between 4k and 2M would be better but then the hardware wont
support that and given that we can have terabytes in a server this may
be feasable now.

Or make order 0 be 64k page like on ARM 64 and Power and then handle
multiple ptes like the implementation years ago by Hugh.