On 2022/6/6 8:03 PM, Michal Hocko wrote:
On Sat 04-06-22 16:22:09, Qi Zheng wrote:
There are already statistics of {pgscan,pgsteal}_kswapd and
{pgscan,pgsteal}_direct of memcg event here, but now only the
sum of the two is displayed in memory.stat of cgroup v2.
In order to obtain more accurate information during monitoring
and debugging, and to align with the display in /proc/vmstat,
it better to display {pgscan,pgsteal}_kswapd and
{pgscan,pgsteal}_direct separately.
Also, for forward compatibility, we still display pgscan and
pgsteal items so that it won't break existing applications.
I do not remember why we have chosen to report cumulative stats rather
than the direct and kswapd parts. Looking back when Roman has introduced
those (http://lkml.kernel.org/r/1494530183-30808-1-git-send-email-guro@xxxxxx)
I do not see any discussion around that. So it was likely just not
a priority.
I have just one question. Say we even decide to have a per memcg kswapd
in some form, would we report that into the same counter?
IMO, I would like it can be reported into the same counter.
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Acked-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
In any case
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks.
One nit below
[...]
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0d3fe0a0c75a..fd78c4d6bbc7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1460,6 +1460,28 @@ static inline unsigned long memcg_page_state_output(struct mem_cgroup *memcg,
return memcg_page_state(memcg, item) * memcg_page_state_unit(item);
}
I would just add the following for clarity
OK, will do.
/* Subset of vm_event_item to report for memcg event stats */
+static const unsigned int memcg_vm_event_stat[] = {
+ PGSCAN_KSWAPD,
+ PGSCAN_DIRECT,
+ PGSTEAL_KSWAPD,
+ PGSTEAL_DIRECT,
+ PGFAULT,
+ PGMAJFAULT,
+ PGREFILL,
+ PGACTIVATE,
+ PGDEACTIVATE,
+ PGLAZYFREE,
+ PGLAZYFREED,
+#if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
+ ZSWPIN,
+ ZSWPOUT,
+#endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ THP_FAULT_ALLOC,
+ THP_COLLAPSE_ALLOC,
+#endif
+};
--
Thanks,
Qi
