Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756311Ab3CQNEp (ORCPT ); Sun, 17 Mar 2013 09:04:45 -0400 Received: from cantor2.suse.de ([195.135.220.15]:51656 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756259Ab3CQNEc (ORCPT ); Sun, 17 Mar 2013 09:04:32 -0400 From: Mel Gorman To: Linux-MM Cc: Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , LKML , Mel Gorman Subject: [PATCH 10/10] mm: vmscan: Move logic from balance_pgdat() to kswapd_shrink_zone() Date: Sun, 17 Mar 2013 13:04:16 +0000 Message-Id: <1363525456-10448-11-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1363525456-10448-1-git-send-email-mgorman@suse.de> References: <1363525456-10448-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5690 Lines: 169 balance_pgdat() is very long and some of the logic can and should be internal to kswapd_shrink_zone(). Move it so the flow of balance_pgdat() is marginally easier to follow. Signed-off-by: Mel Gorman --- mm/vmscan.c | 104 +++++++++++++++++++++++++++++------------------------------- 1 file changed, 51 insertions(+), 53 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 8c66e5a..d7cf384 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2660,18 +2660,53 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining, * reclaim or if the lack of process was due to pages under writeback. */ static bool kswapd_shrink_zone(struct zone *zone, + int classzone_idx, struct scan_control *sc, unsigned long lru_pages, bool shrinking_slab) { + int testorder = sc->order; unsigned long nr_slab = 0; + unsigned long balance_gap; struct reclaim_state *reclaim_state = current->reclaim_state; struct shrink_control shrink = { .gfp_mask = sc->gfp_mask, }; + bool lowmem_pressure; /* Reclaim above the high watermark. */ sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); + + /* + * Kswapd reclaims only single pages with compaction enabled. Trying + * too hard to reclaim until contiguous free pages have become + * available can hurt performance by evicting too much useful data + * from memory. Do not reclaim more than needed for compaction. + */ + if (IS_ENABLED(CONFIG_COMPACTION) && sc->order && + compaction_suitable(zone, sc->order) != + COMPACT_SKIPPED) + testorder = 0; + + /* + * We put equal pressure on every zone, unless one zone has way too + * many pages free already. The "too many pages" is defined as the + * high wmark plus a "gap" where the gap is either the low + * watermark or 1% of the zone, whichever is smaller. + */ + balance_gap = min(low_wmark_pages(zone), + (zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / + KSWAPD_ZONE_BALANCE_GAP_RATIO); + + /* + * If there is no low memory pressure or the zone is balanced then no + * reclaim is necessary + */ + lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone)); + if (!(lowmem_pressure || !zone_balanced(zone, testorder, + balance_gap, classzone_idx))) + return true; + shrink_zone(zone, sc); /* @@ -2689,6 +2724,16 @@ static bool kswapd_shrink_zone(struct zone *zone, zone_clear_flag(zone, ZONE_WRITEBACK); + /* + * If a zone reaches its high watermark, consider it to be no longer + * congested. It's possible there are dirty pages backed by congested + * BDIs but as pressure is relieved, speculatively avoid congestion + * waits. + */ + if (!zone->all_unreclaimable && + zone_balanced(zone, testorder, 0, classzone_idx)) + zone_clear_flag(zone, ZONE_CONGESTED); + return sc->nr_scanned >= sc->nr_to_reclaim; } @@ -2821,8 +2866,6 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, */ for (i = 0; i <= end_zone; i++) { struct zone *zone = pgdat->node_zones + i; - int testorder; - unsigned long balance_gap; if (!populated_zone(zone)) continue; @@ -2843,61 +2886,16 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, sc.nr_reclaimed += nr_soft_reclaimed; /* - * We put equal pressure on every zone, unless - * one zone has way too many pages free - * already. The "too many pages" is defined - * as the high wmark plus a "gap" where the - * gap is either the low watermark or 1% - * of the zone, whichever is smaller. - */ - balance_gap = min(low_wmark_pages(zone), - (zone->managed_pages + - KSWAPD_ZONE_BALANCE_GAP_RATIO-1) / - KSWAPD_ZONE_BALANCE_GAP_RATIO); - /* - * Kswapd reclaims only single pages with compaction - * enabled. Trying too hard to reclaim until contiguous - * free pages have become available can hurt performance - * by evicting too much useful data from memory. - * Do not reclaim more than needed for compaction. + * There should be no need to raise the scanning + * priority if enough pages are already being scanned + * that that high watermark would be met at 100% + * efficiency. */ - testorder = order; - if (IS_ENABLED(CONFIG_COMPACTION) && order && - compaction_suitable(zone, order) != - COMPACT_SKIPPED) - testorder = 0; - - if ((buffer_heads_over_limit && is_highmem_idx(i)) || - !zone_balanced(zone, testorder, - balance_gap, end_zone)) { - /* - * There should be no need to raise the - * scanning priority if enough pages are - * already being scanned that that high - * watermark would be met at 100% efficiency. - */ - if (kswapd_shrink_zone(zone, &sc, + if (kswapd_shrink_zone(zone, end_zone, &sc, lru_pages, shrinking_slab)) raise_priority = false; - nr_to_reclaim += sc.nr_to_reclaim; - } - - if (zone->all_unreclaimable) { - if (end_zone && end_zone == i) - end_zone--; - continue; - } - - if (zone_balanced(zone, testorder, 0, end_zone)) - /* - * If a zone reaches its high watermark, - * consider it to be no longer congested. It's - * possible there are dirty pages backed by - * congested BDIs but as pressure is relieved, - * speculatively avoid congestion waits - */ - zone_clear_flag(zone, ZONE_CONGESTED); + nr_to_reclaim += sc.nr_to_reclaim; } /* -- 1.8.1.4 -- 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/