Messages in this thread | | | Date | Fri, 16 Dec 2011 16:17:31 +0100 | From | Johannes Weiner <> | Subject | Re: [PATCH 11/11] mm: Isolate pages for immediate reclaim on their own LRU |
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On Wed, Dec 14, 2011 at 03:41:33PM +0000, Mel Gorman wrote: > It was observed that scan rates from direct reclaim during tests > writing to both fast and slow storage were extraordinarily high. The > problem was that while pages were being marked for immediate reclaim > when writeback completed, the same pages were being encountered over > and over again during LRU scanning. > > This patch isolates file-backed pages that are to be reclaimed when > clean on their own LRU list.
Excuse me if I sound like a broken record, but have those observations of high scan rates persisted with the per-zone dirty limits patchset?
In my tests with pzd, the scan rates went down considerably together with the immediate reclaim / vmscan writes.
Our dirty limits are pretty low - if reclaim keeps shuffling through dirty pages, where are the 80% reclaimable pages?! To me, this sounds like the unfair distribution of dirty pages among zones again. Is there are a different explanation that I missed?
PS: It also seems a bit out of place in this series...?
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