Messages in this thread |  | | | Date | Fri, 18 Feb 2011 13:18:37 +0900 | | Subject | Re: [PATCH v5 1/4] deactivate invalidated pages | | From | Hiroyuki Kamezawa <> |
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2011/2/18 Minchan Kim <minchan.kim@gmail.com>: > On Fri, Feb 18, 2011 at 12:50 AM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@jp.fujitsu.com> wrote: >> On Fri, 18 Feb 2011 00:08:19 +0900 >> Minchan Kim <minchan.kim@gmail.com> wrote: >> >>> Recently, there are reported problem about thrashing. >>> (http://marc.info/?l=rsync&m=128885034930933&w=2) >>> It happens by backup workloads(ex, nightly rsync). >>> That's because the workload makes just use-once pages >>> and touches pages twice. It promotes the page into >>> active list so that it results in working set page eviction. >>> >>> Some app developer want to support POSIX_FADV_NOREUSE. >>> But other OSes don't support it, either. >>> (http://marc.info/?l=linux-mm&m=128928979512086&w=2) >>> >>> By other approach, app developers use POSIX_FADV_DONTNEED. >>> But it has a problem. If kernel meets page is writing >>> during invalidate_mapping_pages, it can't work. >>> It makes for application programmer to use it since they always >>> have to sync data before calling fadivse(..POSIX_FADV_DONTNEED) to >>> make sure the pages could be discardable. At last, they can't use >>> deferred write of kernel so that they could see performance loss. >>> (http://insights.oetiker.ch/linux/fadvise.html) >>> >>> In fact, invalidation is very big hint to reclaimer. >>> It means we don't use the page any more. So let's move >>> the writing page into inactive list's head if we can't truncate >>> it right now. >>> >>> Why I move page to head of lru on this patch, Dirty/Writeback page >>> would be flushed sooner or later. It can prevent writeout of pageout >>> which is less effective than flusher's writeout. >>> >>> Originally, I reused lru_demote of Peter with some change so added >>> his Signed-off-by. >>> >>> Reported-by: Ben Gamari <bgamari.foss@gmail.com> >>> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> >>> Signed-off-by: Peter Zijlstra <peterz@infradead.org> >>> Acked-by: Rik van Riel <riel@redhat.com> >>> Acked-by: Mel Gorman <mel@csn.ul.ie> >>> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> >>> Cc: Wu Fengguang <fengguang.wu@intel.com> >>> Cc: Johannes Weiner <hannes@cmpxchg.org> >>> Cc: Nick Piggin <npiggin@kernel.dk> >>> Signed-off-by: Minchan Kim <minchan.kim@gmail.com> >> >> >> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> >> One question is ....it seems there is no flush() code for percpu pagevec >> in this patch. Is it safe against cpu hot plug ? >> >> And from memory hot unplug point of view, I'm grad if pagevec for this >> is flushed at the same time as when we clear other per-cpu lru pagevecs. >> (And compaction will be affected by the page_count() magic by pagevec >> which is flushed only when FADVISE is called.) >> >> Could you add add-on patches for flushing and hooks ? > > Isn't it enough in my patch? If I miss your point, Could you elaborate please? > > * Drain pages out of the cpu's pagevecs. > * Either "cpu" is the current CPU, and preemption has already been > * disabled; or "cpu" is being hot-unplugged, and is already dead. > @@ -372,6 +427,29 @@ static void drain_cpu_pagevecs(int cpu) > pagevec_move_tail(pvec); > local_irq_restore(flags); > } > + > + pvec = &per_cpu(lru_deactivate_pvecs, cpu); > + if (pagevec_count(pvec)) > + ____pagevec_lru_deactivate(pvec); > +} >
I'm sorry that I missed this line. It seems I was wrong.
Regards, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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