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Date: Fri, 7 Feb 2014 09:32:00 -0800
From: Andi Kleen <ak@linux.intel.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Anvin <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
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        Matthew Wilcox <willy@linux.intel.com>
Subject: Re: [RFC, PATCH] mm: map few pages around fault address if they are
 in page cache
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> I haven't tested it much, but my kvm boots. There're few places where code
> should be fixed. __do_fault() and filemap_fault() are too ugly and need to
> be cleaned.
> 
> I don't have any performance data yet.
> 
> Any thoughts?

It seems very drastic to do it unconditionally. How about at least a simple
stream detection heuristic and perhaps also madvise?

There are some extreme cases where workloads could use a lot more memory
than before, if they access their memory sparsely in the right pattern.

-Andi