From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 911165F0040 for ; Fri, 22 Oct 2010 00:56:00 -0400 (EDT) Date: Fri, 22 Oct 2010 12:55:54 +0800 From: Wu Fengguang Subject: [PATCH] vmscan: comment too_many_isolated() Message-ID: <20101022045554.GA17073@localhost> References: <20101022045509.GA16804@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101022045509.GA16804@localhost> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Neil Brown , Rik van Riel , KOSAKI Motohiro , KAMEZAWA Hiroyuki , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "Li, Shaohua" List-ID: Comment "Why it's doing so" rather than "What it does" as proposed by Andrew Morton. Reviewed-by: KOSAKI Motohiro Reviewed-by: Minchan Kim Signed-off-by: Wu Fengguang --- mm/vmscan.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- linux-next.orig/mm/vmscan.c 2010-10-19 09:29:44.000000000 +0800 +++ linux-next/mm/vmscan.c 2010-10-19 10:21:41.000000000 +0800 @@ -1142,7 +1142,11 @@ int isolate_lru_page(struct page *page) } /* - * Are there way too many processes in the direct reclaim path already? + * A direct reclaimer may isolate SWAP_CLUSTER_MAX pages from the LRU list and + * then get resheduled. When there are massive number of tasks doing page + * allocation, such sleeping direct reclaimers may keep piling up on each CPU, + * the LRU list will go small and be scanned faster than necessary, leading to + * unnecessary swapping, thrashing and OOM. */ static int too_many_isolated(struct zone *zone, int file, struct scan_control *sc) -- 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/ . Don't email: email@kvack.org