linux-kernel - Re: [PATCH v5 00/11] Introduce huge zero page

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Message-Id: <20121114153243.0f6d6bec.akpm@linux-foundation.org>
Date:	Wed, 14 Nov 2012 15:32:43 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrea Arcangeli <aarcange@...hat.com>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v5 00/11] Introduce huge zero page

On Wed, 14 Nov 2012 23:20:13 +0000
Alan Cox <alan@...rguk.ukuu.org.uk> wrote:

> > I'm still a bit concerned over the possibility that some workloads will
> > cause a high-frequency free/alloc/memset cycle on that huge zero page. 
> > We'll see how it goes...
> 
> That is easy enough to fix - we can delay the freeing by a random time or
> until memory pressure is applied.
> 

The current code does the latter, by freeing the page via a
"slab"-shrinker callback.

But I do suspect that with the right combination of use/unuse and
memory pressure, we could still get into the high-frequency scenario.

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