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Commit 9d998b4f authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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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: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarHillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 30b9aed8

include/trace/events/vmscan.h

+36 −0
Original line number Diff line number Diff line
@@ -363,6 +363,42 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive, 
		show_reclaim_flags(__entry->reclaim_flags))

);



TRACE_EVENT(mm_vmscan_lru_shrink_active,



	TP_PROTO(int nid, unsigned long nr_taken,

		unsigned long nr_active, unsigned long nr_deactivated,

		unsigned long nr_referenced, int priority, int file),



	TP_ARGS(nid, nr_taken, nr_active, nr_deactivated, nr_referenced, priority, file),



	TP_STRUCT__entry(

		__field(int, nid)

		__field(unsigned long, nr_taken)

		__field(unsigned long, nr_active)

		__field(unsigned long, nr_deactivated)

		__field(unsigned long, nr_referenced)

		__field(int, priority)

		__field(int, reclaim_flags)

	),



	TP_fast_assign(

		__entry->nid = nid;

		__entry->nr_taken = nr_taken;

		__entry->nr_active = nr_active;

		__entry->nr_deactivated = nr_deactivated;

		__entry->nr_referenced = nr_referenced;

		__entry->priority = priority;

		__entry->reclaim_flags = trace_shrink_flags(file);

	),



	TP_printk("nid=%d nr_taken=%ld nr_active=%ld nr_deactivated=%ld nr_referenced=%ld priority=%d flags=%s",

		__entry->nid,

		__entry->nr_taken,

		__entry->nr_active, __entry->nr_deactivated, __entry->nr_referenced,

		__entry->priority,

		show_reclaim_flags(__entry->reclaim_flags))

);



#endif /* _TRACE_VMSCAN_H */



/* This part must be outside protection */

mm/vmscan.c

+14 −4
Original line number Diff line number Diff line
@@ -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);

}



/*