A low local/remote numa hinting fault ratio is potentially explained by
failed migrations. This patch adds a tracepoint that fires when migration
fails due to migration rate limitation.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
include/trace/events/migrate.h | 26 ++++++++++++++++++++++++++
mm/migrate.c | 5 ++++-
2 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
index ec2a6cc..3075ffb 100644
--- a/include/trace/events/migrate.h
+++ b/include/trace/events/migrate.h
@@ -45,6 +45,32 @@ TRACE_EVENT(mm_migrate_pages,
__print_symbolic(__entry->reason, MIGRATE_REASON))
);
+TRACE_EVENT(mm_numa_migrate_ratelimit,
+
+ TP_PROTO(struct task_struct *p, int dst_nid, unsigned long nr_pages),
+
+ TP_ARGS(p, dst_nid, nr_pages),
+
+ TP_STRUCT__entry(
+ __array( char, comm, TASK_COMM_LEN)
+ __field( pid_t, pid)
+ __field( int, dst_nid)
+ __field( unsigned long, nr_pages)
+ ),
+
+ TP_fast_assign(
+ memcpy(__entry->comm, p->comm, TASK_COMM_LEN);
+ __entry->pid = p->pid;
+ __entry->dst_nid = dst_nid;
+ __entry->nr_pages = nr_pages;
+ ),
+
+ TP_printk("comm=%s pid=%d dst_nid=%d nr_pages=%lu",
+ __entry->comm,
+ __entry->pid,
+ __entry->dst_nid,
+ __entry->nr_pages)
+);
#endif /* _TRACE_MIGRATE_H */
/* This part must be outside protection */
diff --git a/mm/migrate.c b/mm/migrate.c
index 8b560d5..9f53c00 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1608,8 +1608,11 @@ static bool numamigrate_update_ratelimit(pg_data_t *pgdat,
msecs_to_jiffies(migrate_interval_millisecs);
spin_unlock(&pgdat->numabalancing_migrate_lock);
}
- if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages)
+ if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) {
+ trace_mm_numa_migrate_ratelimit(current, pgdat->node_id,
+ nr_pages);
return true;
+ }
/*
* This is an unlocked non-atomic update so errors are possible.
--
1.8.4
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