Re: [PATCH 7/8] mm: vmscan: Immediately reclaim end-of-LRU dirty pages when writeback completes

On Fri, Jul 22, 2011 at 02:53:48PM +0200, Peter Zijlstra wrote:

On Thu, 2011-07-21 at 17:28 +0100, Mel Gorman wrote:

quoted

When direct reclaim encounters a dirty page, it gets recycled around
the LRU for another cycle. This patch marks the page PageReclaim
similar to deactivate_page() so that the page gets reclaimed almost
immediately after the page gets cleaned. This is to avoid reclaiming
clean pages that are younger than a dirty page encountered at the
end of the LRU that might have been something like a use-once page.

quoted

@@ -834,7 +834,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			 */
 			if (page_is_file_cache(page) &&
 					(!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
-				inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP);
+				/*
+				 * Immediately reclaim when written back.
+				 * Similar in principal to deactivate_page()
+				 * except we already have the page isolated
+				 * and know it's dirty
+				 */
+				inc_zone_page_state(page, NR_VMSCAN_INVALIDATE);
+				SetPageReclaim(page);
+

I find the invalidate name somewhat confusing. It makes me think we'll
drop the page without writeback, like invalidatepage().

I wasn't that happy with it either to be honest but didn't think of a
better one at the time. nr_reclaim_deferred?

-- 
Mel Gorman
SUSE Labs

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