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Message-Id: <20071127120818.d8f9345a.kamezawa.hiroyu@jp.fujitsu.com>
Date: Tue, 27 Nov 2007 12:08:18 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"yamamoto@...inux.co.jp" <yamamoto@...inux.co.jp>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"containers@...ts.osdl.org" <containers@...ts.osdl.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH][for -mm] per-zone and reclaim enhancements for memory
controller take 3 [8/10] modifies vmscan.c for isolate globa/cgroup lru
activity
When using memory controller, there are 2 levels of memory reclaim.
1. zone memory reclaim because of system/zone memory shortage.
2. memory cgroup memory reclaim because of hitting limit.
These two can be distinguished by sc->mem_cgroup parameter.
(scan_global_lru() macro)
This patch tries to make memory cgroup reclaim routine avoid affecting
system/zone memory reclaim. This patch inserts if (scan_global_lru()) and
hook to memory_cgroup reclaim support functions.
This patch can be a help for isolating system lru activity and group lru
activity and shows what additional functions are necessary.
* mem_cgroup_calc_mapped_ratio() ... calculate mapped ratio for cgroup.
* mem_cgroup_reclaim_imbalance() ... calculate active/inactive balance in
cgroup.
* mem_cgroup_calc_reclaim_active() ... calculate the number of active pages to
be scanned in this priority in mem_cgroup.
* mem_cgroup_calc_reclaim_inactive() ... calculate the number of inactive pages
to be scanned in this priority in mem_cgroup.
* mem_cgroup_all_unreclaimable() .. checks cgroup's page is all unreclaimable
or not.
* mem_cgroup_get_reclaim_priority() ...
* mem_cgroup_note_reclaim_priority() ... record reclaim priority (temporal)
* mem_cgroup_remember_reclaim_priority()
.... record reclaim priority as
zone->prev_priority.
This value is used for calc reclaim_mapped.
Changelog V1->V2:
- merged calc_reclaim_mapped patch in previous version.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
mm/vmscan.c | 326 ++++++++++++++++++++++++++++++++++++------------------------
1 file changed, 197 insertions(+), 129 deletions(-)
Index: linux-2.6.24-rc3-mm1/mm/vmscan.c
===================================================================
--- linux-2.6.24-rc3-mm1.orig/mm/vmscan.c 2007-11-26 16:38:46.000000000 +0900
+++ linux-2.6.24-rc3-mm1/mm/vmscan.c 2007-11-26 16:42:38.000000000 +0900
@@ -863,7 +863,8 @@
__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
__mod_zone_page_state(zone, NR_INACTIVE,
-(nr_taken - nr_active));
- zone->pages_scanned += nr_scan;
+ if (scan_global_lru(sc))
+ zone->pages_scanned += nr_scan;
spin_unlock_irq(&zone->lru_lock);
nr_scanned += nr_scan;
@@ -950,6 +951,113 @@
}
/*
+ * Determine we should try to reclaim mapped pages.
+ * This is called only when sc->mem_cgroup is NULL.
+ */
+static int calc_reclaim_mapped(struct scan_control *sc, struct zone *zone,
+ int priority)
+{
+ long mapped_ratio;
+ long distress;
+ long swap_tendency;
+ long imbalance;
+ int reclaim_mapped;
+ int prev_priority;
+
+ if (scan_global_lru(sc) && zone_is_near_oom(zone))
+ return 1;
+ /*
+ * `distress' is a measure of how much trouble we're having
+ * reclaiming pages. 0 -> no problems. 100 -> great trouble.
+ */
+ if (scan_global_lru(sc))
+ prev_priority = zone->prev_priority;
+ else
+ prev_priority = mem_cgroup_get_reclaim_priority(sc->mem_cgroup);
+
+ distress = 100 >> min(prev_priority, priority);
+
+ /*
+ * The point of this algorithm is to decide when to start
+ * reclaiming mapped memory instead of just pagecache. Work out
+ * how much memory
+ * is mapped.
+ */
+ if (scan_global_lru(sc))
+ mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
+ global_page_state(NR_ANON_PAGES)) * 100) /
+ vm_total_pages;
+ else
+ mapped_ratio = mem_cgroup_calc_mapped_ratio(sc->mem_cgroup);
+
+ /*
+ * Now decide how much we really want to unmap some pages. The
+ * mapped ratio is downgraded - just because there's a lot of
+ * mapped memory doesn't necessarily mean that page reclaim
+ * isn't succeeding.
+ *
+ * The distress ratio is important - we don't want to start
+ * going oom.
+ *
+ * A 100% value of vm_swappiness overrides this algorithm
+ * altogether.
+ */
+ swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
+
+ /*
+ * If there's huge imbalance between active and inactive
+ * (think active 100 times larger than inactive) we should
+ * become more permissive, or the system will take too much
+ * cpu before it start swapping during memory pressure.
+ * Distress is about avoiding early-oom, this is about
+ * making swappiness graceful despite setting it to low
+ * values.
+ *
+ * Avoid div by zero with nr_inactive+1, and max resulting
+ * value is vm_total_pages.
+ */
+ if (scan_global_lru(sc)) {
+ imbalance = zone_page_state(zone, NR_ACTIVE);
+ imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
+ } else
+ imbalance = mem_cgroup_reclaim_imbalance(sc->mem_cgroup);
+
+ /*
+ * Reduce the effect of imbalance if swappiness is low,
+ * this means for a swappiness very low, the imbalance
+ * must be much higher than 100 for this logic to make
+ * the difference.
+ *
+ * Max temporary value is vm_total_pages*100.
+ */
+ imbalance *= (vm_swappiness + 1);
+ imbalance /= 100;
+
+ /*
+ * If not much of the ram is mapped, makes the imbalance
+ * less relevant, it's high priority we refill the inactive
+ * list with mapped pages only in presence of high ratio of
+ * mapped pages.
+ *
+ * Max temporary value is vm_total_pages*100.
+ */
+ imbalance *= mapped_ratio;
+ imbalance /= 100;
+
+ /* apply imbalance feedback to swap_tendency */
+ swap_tendency += imbalance;
+
+ /*
+ * Now use this metric to decide whether to start moving mapped
+ * memory onto the inactive list.
+ */
+ if (swap_tendency >= 100)
+ reclaim_mapped = 1;
+
+ return reclaim_mapped;
+}
+
+/*
* This moves pages from the active list to the inactive list.
*
* We move them the other way if the page is referenced by one or more
@@ -966,6 +1074,8 @@
* The downside is that we have to touch page->_count against each page.
* But we had to alter page->flags anyway.
*/
+
+
static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
struct scan_control *sc, int priority)
{
@@ -979,100 +1089,21 @@
struct pagevec pvec;
int reclaim_mapped = 0;
- if (sc->may_swap) {
- long mapped_ratio;
- long distress;
- long swap_tendency;
- long imbalance;
-
- if (zone_is_near_oom(zone))
- goto force_reclaim_mapped;
-
- /*
- * `distress' is a measure of how much trouble we're having
- * reclaiming pages. 0 -> no problems. 100 -> great trouble.
- */
- distress = 100 >> min(zone->prev_priority, priority);
-
- /*
- * The point of this algorithm is to decide when to start
- * reclaiming mapped memory instead of just pagecache. Work out
- * how much memory
- * is mapped.
- */
- mapped_ratio = ((global_page_state(NR_FILE_MAPPED) +
- global_page_state(NR_ANON_PAGES)) * 100) /
- vm_total_pages;
-
- /*
- * Now decide how much we really want to unmap some pages. The
- * mapped ratio is downgraded - just because there's a lot of
- * mapped memory doesn't necessarily mean that page reclaim
- * isn't succeeding.
- *
- * The distress ratio is important - we don't want to start
- * going oom.
- *
- * A 100% value of vm_swappiness overrides this algorithm
- * altogether.
- */
- swap_tendency = mapped_ratio / 2 + distress + sc->swappiness;
-
- /*
- * If there's huge imbalance between active and inactive
- * (think active 100 times larger than inactive) we should
- * become more permissive, or the system will take too much
- * cpu before it start swapping during memory pressure.
- * Distress is about avoiding early-oom, this is about
- * making swappiness graceful despite setting it to low
- * values.
- *
- * Avoid div by zero with nr_inactive+1, and max resulting
- * value is vm_total_pages.
- */
- imbalance = zone_page_state(zone, NR_ACTIVE);
- imbalance /= zone_page_state(zone, NR_INACTIVE) + 1;
-
- /*
- * Reduce the effect of imbalance if swappiness is low,
- * this means for a swappiness very low, the imbalance
- * must be much higher than 100 for this logic to make
- * the difference.
- *
- * Max temporary value is vm_total_pages*100.
- */
- imbalance *= (vm_swappiness + 1);
- imbalance /= 100;
-
- /*
- * If not much of the ram is mapped, makes the imbalance
- * less relevant, it's high priority we refill the inactive
- * list with mapped pages only in presence of high ratio of
- * mapped pages.
- *
- * Max temporary value is vm_total_pages*100.
- */
- imbalance *= mapped_ratio;
- imbalance /= 100;
-
- /* apply imbalance feedback to swap_tendency */
- swap_tendency += imbalance;
-
- /*
- * Now use this metric to decide whether to start moving mapped
- * memory onto the inactive list.
- */
- if (swap_tendency >= 100)
-force_reclaim_mapped:
- reclaim_mapped = 1;
- }
+ if (sc->may_swap)
+ reclaim_mapped = calc_reclaim_mapped(sc, zone, priority);
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
ISOLATE_ACTIVE, zone,
sc->mem_cgroup, 1);
- zone->pages_scanned += pgscanned;
+ /*
+ * zone->pages_scanned is used for detect zone's oom
+ * mem_cgroup remembers nr_scan by itself.
+ */
+ if (scan_global_lru(sc))
+ zone->pages_scanned += pgscanned;
+
__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
spin_unlock_irq(&zone->lru_lock);
@@ -1165,25 +1196,39 @@
unsigned long nr_to_scan;
unsigned long nr_reclaimed = 0;
- /*
- * Add one to `nr_to_scan' just to make sure that the kernel will
- * slowly sift through the active list.
- */
- zone->nr_scan_active +=
- (zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
- nr_active = zone->nr_scan_active;
- if (nr_active >= sc->swap_cluster_max)
- zone->nr_scan_active = 0;
- else
- nr_active = 0;
+ if (scan_global_lru(sc)) {
+ /*
+ * Add one to nr_to_scan just to make sure that the kernel
+ * will slowly sift through the active list.
+ */
+ zone->nr_scan_active +=
+ (zone_page_state(zone, NR_ACTIVE) >> priority) + 1;
+ nr_active = zone->nr_scan_active;
+ zone->nr_scan_inactive +=
+ (zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
+ nr_inactive = zone->nr_scan_inactive;
+ if (nr_inactive >= sc->swap_cluster_max)
+ zone->nr_scan_inactive = 0;
+ else
+ nr_inactive = 0;
+
+ if (nr_active >= sc->swap_cluster_max)
+ zone->nr_scan_active = 0;
+ else
+ nr_active = 0;
+ } else {
+ /*
+ * This reclaim occurs not because zone memory shortage but
+ * because memory controller hits its limit.
+ * Then, don't modify zone reclaim related data.
+ */
+ nr_active = mem_cgroup_calc_reclaim_active(sc->mem_cgroup,
+ zone, priority);
+
+ nr_inactive = mem_cgroup_calc_reclaim_inactive(sc->mem_cgroup,
+ zone, priority);
+ }
- zone->nr_scan_inactive +=
- (zone_page_state(zone, NR_INACTIVE) >> priority) + 1;
- nr_inactive = zone->nr_scan_inactive;
- if (nr_inactive >= sc->swap_cluster_max)
- zone->nr_scan_inactive = 0;
- else
- nr_inactive = 0;
while (nr_active || nr_inactive) {
if (nr_active) {
@@ -1228,25 +1273,39 @@
unsigned long nr_reclaimed = 0;
int i;
+
sc->all_unreclaimable = 1;
for (i = 0; zones[i] != NULL; i++) {
struct zone *zone = zones[i];
if (!populated_zone(zone))
continue;
+ /*
+ * Take care memory controller reclaiming has small influence
+ * to global LRU.
+ */
+ if (scan_global_lru(sc)) {
+ if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ continue;
+ note_zone_scanning_priority(zone, priority);
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
- continue;
-
- note_zone_scanning_priority(zone, priority);
-
- if (zone_is_all_unreclaimable(zone) && priority != DEF_PRIORITY)
- continue; /* Let kswapd poll it */
-
- sc->all_unreclaimable = 0;
+ if (zone_is_all_unreclaimable(zone) &&
+ priority != DEF_PRIORITY)
+ continue; /* Let kswapd poll it */
+ sc->all_unreclaimable = 0;
+ } else {
+ /*
+ * Ignore cpuset limitation here. We just want to reduce
+ * # of used pages by us regardless of memory shortage.
+ */
+ sc->all_unreclaimable = 0;
+ mem_cgroup_note_reclaim_priority(sc->mem_cgroup,
+ priority);
+ }
nr_reclaimed += shrink_zone(priority, zone, sc);
}
+
return nr_reclaimed;
}
@@ -1275,15 +1334,19 @@
int i;
count_vm_event(ALLOCSTALL);
+ /*
+ * mem_cgroup will not do shrink_slab.
+ */
+ if (scan_global_lru(sc)) {
+ for (i = 0; zones[i] != NULL; i++) {
+ struct zone *zone = zones[i];
- for (i = 0; zones[i] != NULL; i++) {
- struct zone *zone = zones[i];
-
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
- continue;
+ if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ continue;
- lru_pages += zone_page_state(zone, NR_ACTIVE)
- + zone_page_state(zone, NR_INACTIVE);
+ lru_pages += zone_page_state(zone, NR_ACTIVE)
+ + zone_page_state(zone, NR_INACTIVE);
+ }
}
for (priority = DEF_PRIORITY; priority >= 0; priority--) {
@@ -1340,14 +1403,19 @@
*/
if (priority < 0)
priority = 0;
- for (i = 0; zones[i] != NULL; i++) {
- struct zone *zone = zones[i];
- if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
- continue;
+ if (scan_global_lru(sc)) {
+ for (i = 0; zones[i] != NULL; i++) {
+ struct zone *zone = zones[i];
+
+ if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
+ continue;
+
+ zone->prev_priority = priority;
+ }
+ } else
+ mem_cgroup_record_reclaim_priority(sc->mem_cgroup, priority);
- zone->prev_priority = priority;
- }
return ret;
}
-
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