From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752902AbcGAPm7 (ORCPT ); Fri, 1 Jul 2016 11:42:59 -0400 Received: from outbound-smtp09.blacknight.com ([46.22.139.14]:49528 "EHLO outbound-smtp09.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751981AbcGAPm4 (ORCPT ); Fri, 1 Jul 2016 11:42:56 -0400 From: Mel Gorman To: Andrew Morton , Linux-MM Cc: Rik van Riel , Vlastimil Babka , Johannes Weiner , LKML , Mel Gorman Subject: [PATCH 29/31] mm: vmstat: account per-zone stalls and pages skipped during reclaim Date: Fri, 1 Jul 2016 16:37:44 +0100 Message-Id: <1467387466-10022-30-git-send-email-mgorman@techsingularity.net> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1467387466-10022-1-git-send-email-mgorman@techsingularity.net> References: <1467387466-10022-1-git-send-email-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The vmstat allocstall was fairly useful in the general sense but node-based LRUs change that. It's important to know if a stall was for an address-limited allocation request as this will require skipping pages from other zones. This patch adds pgstall_* counters to replace allocstall. The sum of the counters will equal the old allocstall so it can be trivially recalculated. A high number of address-limited allocation requests may result in a lot of useless LRU scanning for suitable pages. As address-limited allocations require pages to be skipped, it's important to know how much useless LRU scanning took place so this patch adds pgskip* counters. This yields the following model 1. The number of address-space limited stalls can be accounted for (pgstall) 2. The amount of useless work required to reclaim the data is accounted (pgskip) 3. The total number of scans is available from pgscan_kswapd and pgscan_direct so from that the ratio of useful to useless scans can be calculated. Link: http://lkml.kernel.org/r/1466518566-30034-28-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Cc: Johannes Weiner Cc: Rik van Riel Signed-off-by: Andrew Morton --- include/linux/vm_event_item.h | 4 +++- mm/vmscan.c | 15 +++++++++++++-- mm/vmstat.c | 3 ++- 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index 1798ff542517..6d47f66f0e9c 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -23,6 +23,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, FOR_ALL_ZONES(PGALLOC), + FOR_ALL_ZONES(PGSTALL), + FOR_ALL_ZONES(PGSCAN_SKIP), PGFREE, PGACTIVATE, PGDEACTIVATE, PGFAULT, PGMAJFAULT, PGLAZYFREED, @@ -37,7 +39,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, #endif PGINODESTEAL, SLABS_SCANNED, KSWAPD_INODESTEAL, KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY, - PAGEOUTRUN, ALLOCSTALL, PGROTATED, + PAGEOUTRUN, PGROTATED, DROP_PAGECACHE, DROP_SLAB, #ifdef CONFIG_NUMA_BALANCING NUMA_PTE_UPDATES, diff --git a/mm/vmscan.c b/mm/vmscan.c index a687cfa91166..151c30dd27e2 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1394,6 +1394,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, struct list_head *src = &lruvec->lists[lru]; unsigned long nr_taken = 0; unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 }; + unsigned long nr_skipped[MAX_NR_ZONES] = { 0, }; unsigned long scan, nr_pages; LIST_HEAD(pages_skipped); @@ -1408,6 +1409,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, if (page_zonenum(page) > sc->reclaim_idx) { list_move(&page->lru, &pages_skipped); + nr_skipped[page_zonenum(page)]++; continue; } @@ -1436,8 +1438,17 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan, * scanning would soon rescan the same pages to skip and put the * system at risk of premature OOM. */ - if (!list_empty(&pages_skipped)) + if (!list_empty(&pages_skipped)) { + int zid; + list_splice(&pages_skipped, src); + for (zid = 0; zid < MAX_NR_ZONES; zid++) { + if (!nr_skipped[zid]) + continue; + + __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]); + } + } *nr_scanned = scan; trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan, nr_taken, mode, is_file_lru(lru)); @@ -2676,7 +2687,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, delayacct_freepages_start(); if (global_reclaim(sc)) - count_vm_event(ALLOCSTALL); + __count_zid_vm_events(PGSTALL, sc->reclaim_idx, 1); do { vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup, diff --git a/mm/vmstat.c b/mm/vmstat.c index 905ea9ae2d5a..b9a9844e3142 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -970,6 +970,8 @@ const char * const vmstat_text[] = { "pswpout", TEXTS_FOR_ZONES("pgalloc") + TEXTS_FOR_ZONES("pgstall") + TEXTS_FOR_ZONES("pgskip") "pgfree", "pgactivate", @@ -995,7 +997,6 @@ const char * const vmstat_text[] = { "kswapd_low_wmark_hit_quickly", "kswapd_high_wmark_hit_quickly", "pageoutrun", - "allocstall", "pgrotated", -- 2.6.4