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>
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@ -363,6 +363,42 @@ TRACE_EVENT(mm_vmscan_lru_shrink_inactive,
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show_reclaim_flags(__entry->reclaim_flags))
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);
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TRACE_EVENT(mm_vmscan_lru_shrink_active,
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TP_PROTO(int nid, unsigned long nr_taken,
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unsigned long nr_active, unsigned long nr_deactivated,
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unsigned long nr_referenced, int priority, int file),
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TP_ARGS(nid, nr_taken, nr_active, nr_deactivated, nr_referenced, priority, file),
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TP_STRUCT__entry(
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__field(int, nid)
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__field(unsigned long, nr_taken)
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__field(unsigned long, nr_active)
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__field(unsigned long, nr_deactivated)
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__field(unsigned long, nr_referenced)
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__field(int, priority)
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__field(int, reclaim_flags)
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),
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TP_fast_assign(
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__entry->nid = nid;
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__entry->nr_taken = nr_taken;
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__entry->nr_active = nr_active;
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__entry->nr_deactivated = nr_deactivated;
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__entry->nr_referenced = nr_referenced;
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__entry->priority = priority;
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__entry->reclaim_flags = trace_shrink_flags(file);
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),
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TP_printk("nid=%d nr_taken=%ld nr_active=%ld nr_deactivated=%ld nr_referenced=%ld priority=%d flags=%s",
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__entry->nid,
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__entry->nr_taken,
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__entry->nr_active, __entry->nr_deactivated, __entry->nr_referenced,
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__entry->priority,
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show_reclaim_flags(__entry->reclaim_flags))
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);
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#endif /* _TRACE_VMSCAN_H */
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/* This part must be outside protection */
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18
mm/vmscan.c
18
mm/vmscan.c
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@ -1855,9 +1855,11 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
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*
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* The downside is that we have to touch page->_refcount against each page.
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* But we had to alter page->flags anyway.
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*
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* Returns the number of pages moved to the given lru.
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*/
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static void move_active_pages_to_lru(struct lruvec *lruvec,
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static unsigned move_active_pages_to_lru(struct lruvec *lruvec,
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struct list_head *list,
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struct list_head *pages_to_free,
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enum lru_list lru)
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@ -1866,6 +1868,7 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
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unsigned long pgmoved = 0;
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struct page *page;
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int nr_pages;
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int nr_moved = 0;
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while (!list_empty(list)) {
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page = lru_to_page(list);
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@ -1891,11 +1894,15 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
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spin_lock_irq(&pgdat->lru_lock);
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} else
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list_add(&page->lru, pages_to_free);
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} else {
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nr_moved += nr_pages;
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}
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}
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if (!is_active_lru(lru))
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__count_vm_events(PGDEACTIVATE, pgmoved);
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return nr_moved;
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}
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static void shrink_active_list(unsigned long nr_to_scan,
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@ -1911,7 +1918,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
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LIST_HEAD(l_inactive);
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struct page *page;
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struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
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unsigned long nr_rotated = 0;
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unsigned nr_deactivate, nr_activate;
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unsigned nr_rotated = 0;
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isolate_mode_t isolate_mode = 0;
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int file = is_file_lru(lru);
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struct pglist_data *pgdat = lruvec_pgdat(lruvec);
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@ -1989,13 +1997,15 @@ static void shrink_active_list(unsigned long nr_to_scan,
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*/
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reclaim_stat->recent_rotated[file] += nr_rotated;
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move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
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move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
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nr_activate = move_active_pages_to_lru(lruvec, &l_active, &l_hold, lru);
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nr_deactivate = move_active_pages_to_lru(lruvec, &l_inactive, &l_hold, lru - LRU_ACTIVE);
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__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
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spin_unlock_irq(&pgdat->lru_lock);
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mem_cgroup_uncharge_list(&l_hold);
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free_hot_cold_page_list(&l_hold, true);
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trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_taken, nr_activate,
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nr_deactivate, nr_rotated, sc->priority, file);
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}
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/*
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