Re: [PATCH v17 1/7] mm: support madvise(MADV_FREE)

[Rik van Riel]

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On 02/06/2015 01:32 PM, Shaohua Li wrote:
> On Fri, Feb 06, 2015 at 01:58:25PM +0100, Michal Hocko wrote:
>> On Thu 05-02-15 16:33:11, Shaohua Li wrote: [...]
>>> Did you think about move the MADV_FREE pages to the head of
>>> inactive LRU, so they can be reclaimed easily?
>> 
>> Yes this makes sense for pages living on the active LRU list. I
>> would preserve LRU ordering on the inactive list because there is
>> no good reason to make the operation more costly for inactive
>> pages. On the other hand having tons of to-be-freed pages on the
>> active list clearly sucks. Care to send a patch?
> 
> Considering anon pages are in active LRU first, it's likely
> MADV_FREE pages are in active list. I'm curious why preserves the
> order of inactive list.

Only before the first time MADV_FREE is called on those pages.

If a program repeatedly allocates and frees the same memory
region, not moving the MADV_FREE pages around in the LRU
several times can save some overhead.

- -- 
All rights reversed
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