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 35A9090011B for ; Wed, 13 Jul 2011 10:31:38 -0400 (EDT) From: Mel Gorman Subject: [PATCH 2/5] mm: vmscan: Do not writeback filesystem pages in kswapd except in high priority Date: Wed, 13 Jul 2011 15:31:24 +0100 Message-Id: <1310567487-15367-3-git-send-email-mgorman@suse.de> In-Reply-To: <1310567487-15367-1-git-send-email-mgorman@suse.de> References: <1310567487-15367-1-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Linux-MM Cc: LKML , XFS , Dave Chinner , Christoph Hellwig , Johannes Weiner , Wu Fengguang , Jan Kara , Rik van Riel , Minchan Kim , Mel Gorman It is preferable that no dirty pages are dispatched for cleaning from the page reclaim path. At normal priorities, this patch prevents kswapd writing pages. However, page reclaim does have a requirement that pages be freed in a particular zone. If it is failing to make sufficient progress (reclaiming < SWAP_CLUSTER_MAX at any priority priority), the priority is raised to scan more pages. A priority of DEF_PRIORITY - 3 is considered to tbe the point where kswapd is getting into trouble reclaiming pages. If this priority is reached, kswapd will dispatch pages for writing. Signed-off-by: Mel Gorman --- mm/vmscan.c | 13 ++++++++----- 1 files changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 2d3e5b6..e272951 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -719,7 +719,8 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages) */ static unsigned long shrink_page_list(struct list_head *page_list, struct zone *zone, - struct scan_control *sc) + struct scan_control *sc, + int priority) { LIST_HEAD(ret_pages); LIST_HEAD(free_pages); @@ -827,9 +828,11 @@ static unsigned long shrink_page_list(struct list_head *page_list, /* * Only kswapd can writeback filesystem pages to - * avoid risk of stack overflow + * avoid risk of stack overflow but do not writeback + * unless under significant pressure. */ - if (page_is_file_cache(page) && !current_is_kswapd()) { + if (page_is_file_cache(page) && + (!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) { inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP); goto keep_locked; } @@ -1465,12 +1468,12 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone, spin_unlock_irq(&zone->lru_lock); - nr_reclaimed = shrink_page_list(&page_list, zone, sc); + nr_reclaimed = shrink_page_list(&page_list, zone, sc, priority); /* Check if we should syncronously wait for writeback */ if (should_reclaim_stall(nr_taken, nr_reclaimed, priority, sc)) { set_reclaim_mode(priority, sc, true); - nr_reclaimed += shrink_page_list(&page_list, zone, sc); + nr_reclaimed += shrink_page_list(&page_list, zone, sc, priority); } local_irq_disable(); -- 1.7.3.4 -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org