* [PATCH] mm: avoid taking zone lock in pagetypeinfo_showmixed
@ 2017-06-21 11:47 Vinayak Menon
2017-06-21 12:24 ` Vlastimil Babka
0 siblings, 1 reply; 2+ messages in thread
From: Vinayak Menon @ 2017-06-21 11:47 UTC (permalink / raw)
To: akpm, vbabka, iamjoonsoo.kim, zhongjiang, sergey.senozhatsky,
sudipm.mukherjee, hannes, mgorman, mhocko, bigeasy, rientjes,
minchan
Cc: linux-mm, Vinayak Menon
pagetypeinfo_showmixedcount_print is found to take a lot of
time to complete and it does this holding the zone lock and
disabling interrupts. In some cases it is found to take more
than a second (On a 2.4GHz,8Gb RAM,arm64 cpu). Avoid taking
the zone lock similar to what is done by read_page_owner,
which means possibility of inaccurate results.
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
---
mm/page_owner.c | 6 +++++-
mm/vmstat.c | 24 ++++++++++++++----------
2 files changed, 19 insertions(+), 11 deletions(-)
diff --git a/mm/page_owner.c b/mm/page_owner.c
index c3cee24..401feb0 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -281,7 +281,11 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
continue;
if (PageBuddy(page)) {
- pfn += (1UL << page_order(page)) - 1;
+ unsigned long freepage_order;
+
+ freepage_order = page_order_unsafe(page);
+ if (freepage_order < MAX_ORDER)
+ pfn += (1UL << freepage_order) - 1;
continue;
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f5fa1bd..8cefdad 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1129,7 +1129,7 @@ static void frag_stop(struct seq_file *m, void *arg)
* If @assert_populated is true, only use callback for zones that are populated.
*/
static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
- bool assert_populated,
+ bool assert_populated, bool nolock,
void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
{
struct zone *zone;
@@ -1140,9 +1140,11 @@ static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
if (assert_populated && !populated_zone(zone))
continue;
- spin_lock_irqsave(&zone->lock, flags);
+ if (!nolock)
+ spin_lock_irqsave(&zone->lock, flags);
print(m, pgdat, zone);
- spin_unlock_irqrestore(&zone->lock, flags);
+ if (!nolock)
+ spin_unlock_irqrestore(&zone->lock, flags);
}
}
#endif
@@ -1165,7 +1167,7 @@ static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
static int frag_show(struct seq_file *m, void *arg)
{
pg_data_t *pgdat = (pg_data_t *)arg;
- walk_zones_in_node(m, pgdat, true, frag_show_print);
+ walk_zones_in_node(m, pgdat, true, false, frag_show_print);
return 0;
}
@@ -1206,7 +1208,7 @@ static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
seq_printf(m, "%6d ", order);
seq_putc(m, '\n');
- walk_zones_in_node(m, pgdat, true, pagetypeinfo_showfree_print);
+ walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
return 0;
}
@@ -1258,7 +1260,8 @@ static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
seq_printf(m, "%12s ", migratetype_names[mtype]);
seq_putc(m, '\n');
- walk_zones_in_node(m, pgdat, true, pagetypeinfo_showblockcount_print);
+ walk_zones_in_node(m, pgdat, true, false,
+ pagetypeinfo_showblockcount_print);
return 0;
}
@@ -1284,7 +1287,8 @@ static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
seq_printf(m, "%12s ", migratetype_names[mtype]);
seq_putc(m, '\n');
- walk_zones_in_node(m, pgdat, true, pagetypeinfo_showmixedcount_print);
+ walk_zones_in_node(m, pgdat, true, true,
+ pagetypeinfo_showmixedcount_print);
#endif /* CONFIG_PAGE_OWNER */
}
@@ -1448,7 +1452,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
static int zoneinfo_show(struct seq_file *m, void *arg)
{
pg_data_t *pgdat = (pg_data_t *)arg;
- walk_zones_in_node(m, pgdat, false, zoneinfo_show_print);
+ walk_zones_in_node(m, pgdat, false, false, zoneinfo_show_print);
return 0;
}
@@ -1854,7 +1858,7 @@ static int unusable_show(struct seq_file *m, void *arg)
if (!node_state(pgdat->node_id, N_MEMORY))
return 0;
- walk_zones_in_node(m, pgdat, true, unusable_show_print);
+ walk_zones_in_node(m, pgdat, true, false, unusable_show_print);
return 0;
}
@@ -1906,7 +1910,7 @@ static int extfrag_show(struct seq_file *m, void *arg)
{
pg_data_t *pgdat = (pg_data_t *)arg;
- walk_zones_in_node(m, pgdat, true, extfrag_show_print);
+ walk_zones_in_node(m, pgdat, true, false, extfrag_show_print);
return 0;
}
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mm: avoid taking zone lock in pagetypeinfo_showmixed
2017-06-21 11:47 [PATCH] mm: avoid taking zone lock in pagetypeinfo_showmixed Vinayak Menon
@ 2017-06-21 12:24 ` Vlastimil Babka
0 siblings, 0 replies; 2+ messages in thread
From: Vlastimil Babka @ 2017-06-21 12:24 UTC (permalink / raw)
To: Vinayak Menon, akpm, iamjoonsoo.kim, zhongjiang,
sergey.senozhatsky, sudipm.mukherjee, hannes, mgorman, mhocko,
bigeasy, rientjes, minchan
Cc: linux-mm
On 06/21/2017 01:47 PM, Vinayak Menon wrote:
> pagetypeinfo_showmixedcount_print is found to take a lot of
> time to complete and it does this holding the zone lock and
> disabling interrupts. In some cases it is found to take more
> than a second (On a 2.4GHz,8Gb RAM,arm64 cpu). Avoid taking
> the zone lock similar to what is done by read_page_owner,
> which means possibility of inaccurate results.
>
> Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
walk_zones_in_node() becomes quite ugly though, multiple bool params are
not nice, and both are there for single special cases. Wonder if
replacing this with a new for_each_zone_node() helper would make this
better. OTOH it's now isolated only to vmstat.c.
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