mm, vmscan: add active list aging tracepoint
Our reclaim process has several tracepoints to tell us more about how
things are progressing. We are, however, missing a tracepoint to track
active list aging. Introduce mm_vmscan_lru_shrink_active which reports
the number of
- nr_taken is number of isolated pages from the active list
- nr_referenced pages which tells us that we are hitting referenced
pages which are deactivated. If this is a large part of the
reported nr_deactivated pages then we might be hitting into
the active list too early because they might be still part of
the working set. This might help to debug performance issues.
- nr_active pages which tells us how many pages are kept on the
active list - mostly exec file backed pages. A high number can
indicate that we might be trashing on executables.
[mhocko@suse.com: update]
Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 532a2a75..a34bf51d 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1855,9 +1855,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
*
* The downside is that we have to touch page->_refcount against each page.
* But we had to alter page->flags anyway.
+ *
+ * Returns the number of pages moved to the given lru.
*/
-static void move_active_pages_to_lru(struct lruvec *lruvec,
+static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
struct list_head *list,
struct list_head *pages_to_free,
enum lru_list lru)
@@ -1866,6 +1868,7 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
unsigned long pgmoved = 0;
struct page *page;
int nr_pages;
+ int nr_moved = 0;
while (!list_empty(list)) {
page = lru_to_page(list);
@@ -1891,11 +1894,15 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
spin_lock_irq(&pgdat->lru_lock);
} else
list_add(&page->lru, pages_to_free);
+ } else {
+ nr_moved += nr_pages;
}
}
if (!is_active_lru(lru))
__count_vm_events(PGDEACTIVATE, pgmoved);
+
+ return nr_moved;
}
static void shrink_active_list(unsigned long nr_to_scan,
@@ -1911,7 +1918,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
LIST_HEAD(l_inactive);
struct page *page;
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
- unsigned long nr_rotated = 0;
+ unsigned nr_deactivate, nr_activate;
+ unsigned nr_rotated = 0;
isolate_mode_t isolate_mode = 0;
int file = is_file_lru(lru);
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
@@ -1989,13 +1997,15 @@ static void shrink_active_list(unsigned long nr_to_scan,
*/
reclaim_stat->recent_rotated[file] += nr_rotated;
- move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
- move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
+ nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
+ nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
spin_unlock_irq(&pgdat->lru_lock);
mem_cgroup_uncharge_list(&l_hold);
free_hot_cold_page_list(&l_hold, true);
+ trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
+ nr_deactivate, nr_rotated, sc->priority, file);
}
/*
