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Message-Id: <20091215092654.CDB3.A69D9226@jp.fujitsu.com>
Date: Tue, 15 Dec 2009 09:35:41 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: Minchan Kim <minchan.kim@...il.com>
Cc: kosaki.motohiro@...fujitsu.com, Rik van Riel <riel@...hat.com>,
lwoodman@...hat.com, akpm@...ux-foundation.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/8] Stop reclaim quickly when the task reclaimed enough lots pages
> On Mon, 14 Dec 2009 21:31:36 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:
>
> >
> > From latency view, There isn't any reason shrink_zones() continue to
> > reclaim another zone's page if the task reclaimed enough lots pages.
> >
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> > ---
> > mm/vmscan.c | 16 ++++++++++++----
> > 1 files changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 0880668..bf229d3 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1654,7 +1654,7 @@ static void shrink_zone_end(struct zone *zone, struct scan_control *sc)
> > /*
> > * This is a basic per-zone page freer. Used by both kswapd and direct reclaim.
> > */
> > -static void shrink_zone(int priority, struct zone *zone,
> > +static int shrink_zone(int priority, struct zone *zone,
> > struct scan_control *sc)
> > {
> > unsigned long nr[NR_LRU_LISTS];
> > @@ -1669,7 +1669,7 @@ static void shrink_zone(int priority, struct zone *zone,
> >
> > ret = shrink_zone_begin(zone, sc);
> > if (ret)
> > - return;
> > + return ret;
> >
> > /* If we have no swap space, do not bother scanning anon pages. */
> > if (!sc->may_swap || (nr_swap_pages <= 0)) {
> > @@ -1692,6 +1692,7 @@ static void shrink_zone(int priority, struct zone *zone,
> > &reclaim_stat->nr_saved_scan[l]);
> > }
> >
> > + ret = 0;
> > while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
> > nr[LRU_INACTIVE_FILE]) {
> > for_each_evictable_lru(l) {
> > @@ -1712,8 +1713,10 @@ static void shrink_zone(int priority, struct zone *zone,
> > * with multiple processes reclaiming pages, the total
> > * freeing target can get unreasonably large.
> > */
> > - if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
> > + if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY) {
> > + ret = -ERESTARTSYS;
>
> Just nitpick.
>
> shrink_zone's return value is matter?
> shrink_zones never handle that.
shrink_zones() stop vmscan quickly if ret isn't !0.
if we already scanned rather than nr_to_reclaim, we can stop vmscan.
> As a matter of fact, I am worried about this patch.
>
> My opinion is we put aside this patch until we can solve Larry's problem.
> We could apply this patch in future.
>
> I don't want to see the side effect while we focus Larry's problem.
> But If you mind my suggestion, I also will not bother you by this nitpick.
>
> Thanks for great cleanup and improving VM, Kosaki. :)
I agree with Larry's issue is highest priority.
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