Re: mm: used-once mapped file page detection

[Rik van Riel <riel@redhat.com>]

On 02/26/2010 09:32 AM, Johannes Weiner wrote:
> On Wed, Feb 24, 2010 at 01:39:46PM -0800, Andrew Morton wrote:
>> On Mon, 22 Feb 2010 20:49:07 +0100 Johannes Weiner<hannes@cmpxchg.org>  wrote:
>>
>>> This patch makes the VM be more careful about activating mapped file
>>> pages in the first place.  The minimum granted lifetime without
>>> another memory access becomes an inactive list cycle instead of the
>>> full memory cycle, which is more natural given the mentioned loads.
>>
>> iirc from a long time ago, the insta-activation of mapped pages was
>> done because people were getting peeved about having their interactive
>> applications (X, browser, etc) getting paged out, and bumping the pages
>> immediately was found to help with this subjective problem.
>>
>> So it was a latency issue more than a throughput issue.  I wouldn't be
>> surprised if we get some complaints from people for the same reasons as
>> a result of this patch.
>
> Agreed.  Although we now have other things in place to protect them once
> they are active (VM_EXEC protection, lazy active list scanning).

You think we'll need VM_EXEC protection on the inactive list
after your changes?

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