linux-kernel - Re: Free memory never fully used, swapping

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Date:	Tue, 30 Nov 2010 13:13:46 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	Simon Kirby <sim@...tway.ca>
cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: Free memory never fully used, swapping

On Tue, 30 Nov 2010, Simon Kirby wrote:

> Can we also mess with these /sys files on the fly?

Sure. Go ahead. These are runtime configurable.

> I'm not familiar with how slub works, but I assume there's some overhead
> or some reason not to just use order 0 for <= kmalloc-4096?  Or is it
> purely just trying to reduce cpu by calling alloc_pages less often?

Using higher order pages reduces the memory overhead for objects (that
after all need to be packed into an order N page), decreases the amount
of metadata that needs to be managed and decreases the use of the
slowpaths. That implies also a reduction in the locking overhead.


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