readahead: retain inactive lru pages to be accessed soon
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From: Wu Fengguang on 25 Feb 2010 07:30 On Thu, Feb 25, 2010 at 11:17:41AM +0800, Rik van Riel wrote: > On 02/23/2010 10:10 PM, Wu Fengguang wrote: > > From: Chris Frost<frost(a)cs.ucla.edu> > > > > Ensure that cached pages in the inactive list are not prematurely evicted; > > move such pages to lru head when they are covered by > > - in-kernel heuristic readahead > > - an posix_fadvise(POSIX_FADV_WILLNEED) hint from an application > > > Signed-off-by: Chris Frost<frost(a)cs.ucla.edu> > > Signed-off-by: Steve VanDeBogart<vandebo(a)cs.ucla.edu> > > Signed-off-by: KAMEZAWA Hiroyuki<kamezawa.hiroyu(a)jp.fujitsu.com> > > Signed-off-by: Wu Fengguang<fengguang.wu(a)intel.com> > > Acked-by: Rik van Riel <riel(a)redhat.com> > > When we get into the situation where readahead thrashing > would occur, we will end up evicting other stuff more > quickly from the inactive file list. However, that will > be the case either with or without this code... Thanks. I'm actually not afraid of it adding memory pressure to the readahead thrashing case. The context readahead (patch 07) can adaptively control the memory pressure with or without this patch. It does add memory pressure to mmap read-around. A typical read-around request would cover some cached pages (whether or not they are memory-mapped), and all those pages would be moved to LRU head by this patch. This somehow implicitly adds LRU lifetime to executable/lib pages. Hopefully this won't behave too bad. And will be limited by smaller readahead size in small memory systems (patch 05). Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |