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Date: Thu, 29 Dec 2016 14:33:59 +0900
From: Minchan Kim <minchan@...nel.org>
To: Michal Hocko <mhocko@...nel.org>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...e.de>,
Johannes Weiner <hannes@...xchg.org>,
Vlastimil Babka <vbabka@...e.cz>,
Rik van Riel <riel@...hat.com>,
LKML <linux-kernel@...r.kernel.org>,
Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint
On Wed, Dec 28, 2016 at 04:30:27PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
>
> 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 scanned, rotated, deactivated and freed pages from the
> particular node's active list.
>
> Signed-off-by: Michal Hocko <mhocko@...e.com>
> ---
> include/linux/gfp.h | 2 +-
> include/trace/events/vmscan.h | 38 ++++++++++++++++++++++++++++++++++++++
> mm/page_alloc.c | 6 +++++-
> mm/vmscan.c | 22 +++++++++++++++++-----
> 4 files changed, 61 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 4175dca4ac39..61aa9b49e86d 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -503,7 +503,7 @@ void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask);
> extern void __free_pages(struct page *page, unsigned int order);
> extern void free_pages(unsigned long addr, unsigned int order);
> extern void free_hot_cold_page(struct page *page, bool cold);
> -extern void free_hot_cold_page_list(struct list_head *list, bool cold);
> +extern int free_hot_cold_page_list(struct list_head *list, bool cold);
>
> struct page_frag_cache;
> extern void __page_frag_drain(struct page *page, unsigned int order,
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index 39bad8921ca1..d34cc0ced2be 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -363,6 +363,44 @@ 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_scanned, unsigned long nr_freed,
> + unsigned long nr_unevictable, unsigned long nr_deactivated,
> + unsigned long nr_rotated, int priority, int file),
> +
> + TP_ARGS(nid, nr_scanned, nr_freed, nr_unevictable, nr_deactivated, nr_rotated, priority, file),
I agree it is helpful. And it was when I investigated aging problem of 32bit
when node-lru was introduced. However, the question is we really need all those
kinds of information? just enough with nr_taken, nr_deactivated, priority, file?
Also, look at minor thing below.
Thanks.
> +
> + TP_STRUCT__entry(
> + __field(int, nid)
> + __field(unsigned long, nr_scanned)
> + __field(unsigned long, nr_freed)
> + __field(unsigned long, nr_unevictable)
> + __field(unsigned long, nr_deactivated)
> + __field(unsigned long, nr_rotated)
> + __field(int, priority)
> + __field(int, reclaim_flags)
> + ),
> +
> + TP_fast_assign(
> + __entry->nid = nid;
> + __entry->nr_scanned = nr_scanned;
> + __entry->nr_freed = nr_freed;
> + __entry->nr_unevictable = nr_unevictable;
> + __entry->nr_deactivated = nr_deactivated;
> + __entry->nr_rotated = nr_rotated;
> + __entry->priority = priority;
> + __entry->reclaim_flags = trace_shrink_flags(file);
> + ),
> +
> + TP_printk("nid=%d nr_scanned=%ld nr_freed=%ld nr_unevictable=%ld nr_deactivated=%ld nr_rotated=%ld priority=%d flags=%s",
> + __entry->nid,
> + __entry->nr_scanned, __entry->nr_freed, __entry->nr_unevictable,
> + __entry->nr_deactivated, __entry->nr_rotated,
> + __entry->priority,
> + show_reclaim_flags(__entry->reclaim_flags))
> +);
> +
> #endif /* _TRACE_VMSCAN_H */
>
> /* This part must be outside protection */
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1c24112308d6..77d204660857 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2487,14 +2487,18 @@ void free_hot_cold_page(struct page *page, bool cold)
> /*
> * Free a list of 0-order pages
> */
> -void free_hot_cold_page_list(struct list_head *list, bool cold)
> +int free_hot_cold_page_list(struct list_head *list, bool cold)
> {
> struct page *page, *next;
> + int ret = 0;
>
> list_for_each_entry_safe(page, next, list, lru) {
> trace_mm_page_free_batched(page, cold);
> free_hot_cold_page(page, cold);
> + ret++;
> }
> +
> + return ret;
> }
>
> /*
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index c4abf08861d2..2302a1a58c6e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1846,9 +1846,11 @@ 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 int move_active_pages_to_lru(struct lruvec *lruvec,
> struct list_head *list,
> struct list_head *pages_to_free,
> enum lru_list lru)
> @@ -1857,6 +1859,7 @@ 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);
> @@ -1882,11 +1885,15 @@ 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++;
> }
> }
>
> if (!is_active_lru(lru))
> __count_vm_events(PGDEACTIVATE, pgmoved);
> +
> + return nr_moved;
> }
>
> static void shrink_active_list(unsigned long nr_to_scan,
> @@ -1902,7 +1909,8 @@ 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 long nr_rotated = 0, nr_unevictable = 0;
> + unsigned long nr_freed, nr_deactivate, nr_activate;
> isolate_mode_t isolate_mode = 0;
> int file = is_file_lru(lru);
> struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> @@ -1935,6 +1943,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>
> if (unlikely(!page_evictable(page))) {
> putback_lru_page(page);
> + nr_unevictable++;
> continue;
> }
>
> @@ -1980,13 +1989,16 @@ 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);
Who use nr_active in here?
> + 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);
> + nr_freed = free_hot_cold_page_list(&l_hold, true);
> + trace_mm_vmscan_lru_shrink_active(pgdat->node_id, nr_scanned, nr_freed,
> + nr_unevictable, nr_deactivate, nr_rotated,
> + sc->priority, file);
> }
>
> /*
> --
> 2.10.2
>
> --
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