Re: [patch] mm, compaction: add vmstats for kcompactd work
From: Vlastimil Babka
Date: Thu Dec 08 2016 - 03:04:21 EST
On 12/08/2016 02:50 AM, David Rientjes wrote:
A "compact_daemon_wake" vmstat exists that represents the number of times
kcompactd has woken up. This doesn't represent how much work it actually
did, though.
It's useful to understand how much compaction work is being done by
kcompactd versus other methods such as direct compaction and explicitly
triggered per-node (or system) compaction.
This adds two new vmstats: "compact_daemon_migrate_scanned" and
"compact_daemon_free_scanned" to represent the number of pages kcompactd
has scanned as part of its migration scanner and freeing scanner,
respectively.
These values are still accounted for in the general
"compact_migrate_scanned" and "compact_free_scanned" for compatibility.
It could be argued that explicitly triggered compaction could also be
tracked separately, and that could be added if others find it useful.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
A bit of downside is that stats are only updated when compaction
finishes, but I guess it's acceptable. Also I don't think the
compact_control variables need the "total_" prefix, but no strong
feelings. The explicit zero init should be also unnecessary.
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
include/linux/vm_event_item.h | 1 +
mm/compaction.c | 22 +++++++++++++++++++---
mm/internal.h | 2 ++
mm/vmstat.c | 2 ++
4 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -56,6 +56,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
COMPACTISOLATED,
COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
KCOMPACTD_WAKE,
+ KCOMPACTD_MIGRATE_SCANNED, KCOMPACTD_FREE_SCANNED,
#endif
#ifdef CONFIG_HUGETLB_PAGE
HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -548,7 +548,7 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
if (blockpfn == end_pfn)
update_pageblock_skip(cc, valid_page, total_isolated, false);
- count_compact_events(COMPACTFREE_SCANNED, nr_scanned);
+ cc->total_free_scanned += nr_scanned;
if (total_isolated)
count_compact_events(COMPACTISOLATED, total_isolated);
return total_isolated;
@@ -939,7 +939,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
trace_mm_compaction_isolate_migratepages(start_pfn, low_pfn,
nr_scanned, nr_isolated);
- count_compact_events(COMPACTMIGRATE_SCANNED, nr_scanned);
+ cc->total_migrate_scanned += nr_scanned;
if (nr_isolated)
count_compact_events(COMPACTISOLATED, nr_isolated);
@@ -1643,6 +1643,9 @@ static enum compact_result compact_zone(struct zone *zone, struct compact_contro
zone->compact_cached_free_pfn = free_pfn;
}
+ count_compact_events(COMPACTMIGRATE_SCANNED, cc->total_migrate_scanned);
+ count_compact_events(COMPACTFREE_SCANNED, cc->total_free_scanned);
+
trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
cc->free_pfn, end_pfn, sync, ret);
@@ -1657,6 +1660,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
struct compact_control cc = {
.nr_freepages = 0,
.nr_migratepages = 0,
+ .total_migrate_scanned = 0,
+ .total_free_scanned = 0,
.order = order,
.gfp_mask = gfp_mask,
.zone = zone,
@@ -1767,6 +1772,8 @@ static void compact_node(int nid)
struct zone *zone;
struct compact_control cc = {
.order = -1,
+ .total_migrate_scanned = 0,
+ .total_free_scanned = 0,
.mode = MIGRATE_SYNC,
.ignore_skip_hint = true,
.whole_zone = true,
@@ -1892,6 +1899,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
struct zone *zone;
struct compact_control cc = {
.order = pgdat->kcompactd_max_order,
+ .total_migrate_scanned = 0,
+ .total_free_scanned = 0,
.classzone_idx = pgdat->kcompactd_classzone_idx,
.mode = MIGRATE_SYNC_LIGHT,
.ignore_skip_hint = true,
@@ -1899,7 +1908,7 @@ static void kcompactd_do_work(pg_data_t *pgdat)
};
trace_mm_compaction_kcompactd_wake(pgdat->node_id, cc.order,
cc.classzone_idx);
- count_vm_event(KCOMPACTD_WAKE);
+ count_compact_event(KCOMPACTD_WAKE);
for (zoneid = 0; zoneid <= cc.classzone_idx; zoneid++) {
int status;
@@ -1917,6 +1926,8 @@ static void kcompactd_do_work(pg_data_t *pgdat)
cc.nr_freepages = 0;
cc.nr_migratepages = 0;
+ cc.total_migrate_scanned = 0;
+ cc.total_free_scanned = 0;
cc.zone = zone;
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
@@ -1935,6 +1946,11 @@ static void kcompactd_do_work(pg_data_t *pgdat)
defer_compaction(zone, cc.order);
}
+ count_compact_events(KCOMPACTD_MIGRATE_SCANNED,
+ cc.total_migrate_scanned);
+ count_compact_events(KCOMPACTD_FREE_SCANNED,
+ cc.total_free_scanned);
+
VM_BUG_ON(!list_empty(&cc.freepages));
VM_BUG_ON(!list_empty(&cc.migratepages));
}
diff --git a/mm/internal.h b/mm/internal.h
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -173,6 +173,8 @@ struct compact_control {
struct list_head migratepages; /* List of pages being migrated */
unsigned long nr_freepages; /* Number of isolated free pages */
unsigned long nr_migratepages; /* Number of pages to migrate */
+ unsigned long total_migrate_scanned;
+ unsigned long total_free_scanned;
unsigned long free_pfn; /* isolate_freepages search base */
unsigned long migrate_pfn; /* isolate_migratepages search base */
unsigned long last_migrated_pfn;/* Not yet flushed page being freed */
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1038,6 +1038,8 @@ const char * const vmstat_text[] = {
"compact_fail",
"compact_success",
"compact_daemon_wake",
+ "compact_daemon_migrate_scanned",
+ "compact_daemon_free_scanned",
#endif
#ifdef CONFIG_HUGETLB_PAGE
--
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