From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 92B3D6B0087 for ; Fri, 10 Dec 2010 05:37:02 -0500 (EST) Date: Fri, 10 Dec 2010 10:36:42 +0000 From: Mel Gorman Subject: Re: [PATCH 3/6] mm: kswapd: Use the order that kswapd was reclaiming at for sleeping_prematurely() Message-ID: <20101210103642.GK20133@csn.ul.ie> References: <1291893500-12342-1-git-send-email-mel@csn.ul.ie> <1291893500-12342-4-git-send-email-mel@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Simon Kirby , KOSAKI Motohiro , Shaohua Li , Dave Hansen , Johannes Weiner , Andrew Morton , linux-mm , linux-kernel List-ID: On Fri, Dec 10, 2010 at 10:16:19AM +0900, Minchan Kim wrote: > On Thu, Dec 9, 2010 at 8:18 PM, Mel Gorman wrote: > > Before kswapd goes to sleep, it uses sleeping_prematurely() to check if > > there was a race pushing a zone below its watermark. If the race > > happened, it stays awake. However, balance_pgdat() can decide to reclaim > > at a lower order if it decides that high-order reclaim is not working as > > Could you specify "order-0" explicitly instead of "a lower order"? > It makes more clear to me. > Done. > > expected. This information is not passed back to sleeping_prematurely(). > > The impact is that kswapd remains awake reclaiming pages long after it > > should have gone to sleep. This patch passes the adjusted order to > > sleeping_prematurely and uses the same logic as balance_pgdat to decide > > if it's ok to go to sleep. > > > > Signed-off-by: Mel Gorman > Reviewed-by: Minchan Kim > > A comment below. > > > --- > > mm/vmscan.c | 14 ++++++++++---- > > 1 files changed, 10 insertions(+), 4 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index b4472a1..52e229e 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -2132,7 +2132,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, unsigned long balanced) > > } > > > > /* is kswapd sleeping prematurely? */ > > -static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > > +static bool sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > > { > > int i; > > unsigned long balanced = 0; > > @@ -2142,7 +2142,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining) > > if (remaining) > > return 1; > > > > - /* If after HZ/10, a zone is below the high mark, it's premature */ > > + /* Check the watermark levels */ > > for (i = 0; i < pgdat->nr_zones; i++) { > > struct zone *zone = pgdat->node_zones + i; > > > > @@ -2427,7 +2427,13 @@ out: > > } > > } > > > > - return sc.nr_reclaimed; > > + /* > > + * Return the order we were reclaiming at so sleeping_prematurely() > > + * makes a decision on the order we were last reclaiming at. However, > > + * if another caller entered the allocator slow path while kswapd > > + * was awake, order will remain at the higher level > > + */ > > + return order; > > } > > Please change return value description of balance_pgdat. > "Returns the number of pages which were actually freed" > Oops, done. Thanks -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org