Thread (7 messages) 7 messages, 5 authors, 2011-08-08

Re: [PATCH v2] vmscan: reverse lru scanning order

From: Minchan Kim <hidden>
Date: 2011-08-08 22:30:50
Also in: lkml

On Mon, Aug 8, 2011 at 9:22 PM, Michal Hocko [off-list ref] wrote:
On Mon 08-08-11 15:02:07, Konstantin Khlebnikov wrote:
quoted
LRU scanning order was accidentially changed in commit v2.6.27-5584-gb69408e:
"vmscan: Use an indexed array for LRU variables".
Before that commit reclaimer always scan active lists first.

This patch just reverse it back.
I am still not sure I see why the ordering matters that much.
One thing that might matter is that shrink_list moves some pages from
active to inactive list if inactive is low so it makes sense to try to
shrink active before inactive. It would be a problem if inactive was
almost empty. Then we would just waste time by shrinking inactive first.
I am not sure how real problem is that, though.

Whatever is the reason, I think it should be documented in the
changelog.
The change makes sense to me.
Absolutely agree with Michal.
I think the patch itself doesn't have a problem and even it is does make sense.
But we need changelog why we need it.
I don't want to overwrite recent git log without any issue.
It annoys us when we find a bug by git-blame. ;-)
-- 
Kind regards,
Minchan Kim

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