[PATCH 2/2] mm, memcontrol: Implement memory.swap.events
From: Tejun Heo <tj@kernel.org>
Date: 2018-03-24 16:52:00
Also in:
linux-api, linux-mm, lkml
Subsystem:
control group - memory resource controller (memcg), documentation, memory management, the rest · Maintainers:
Johannes Weiner, Michal Hocko, Roman Gushchin, Shakeel Butt, Jonathan Corbet, Andrew Morton, Linus Torvalds
Add swap max and fail events so that userland can monitor and respond to running out of swap. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <redacted> Cc: Roman Gushchin <redacted> Cc: Rik van Riel <riel@surriel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-api@vger.kernel.org --- Documentation/cgroup-v2.txt | 16 ++++++++++++++++ include/linux/memcontrol.h | 5 +++++ mm/memcontrol.c | 24 +++++++++++++++++++++++- 3 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
index 74cdeae..b0dda10 100644
--- a/Documentation/cgroup-v2.txt
+++ b/Documentation/cgroup-v2.txt@@ -1199,6 +1199,22 @@ PAGE_SIZE multiple when read back. Swap usage hard limit. If a cgroup's swap usage reaches this limit, anonymous memory of the cgroup will not be swapped out. + memory.swap.events + A read-only flat-keyed file which exists on non-root cgroups. + The following entries are defined. Unless specified + otherwise, a value change in this file generates a file + modified event. + + max + The number of times the cgroup's swap usage was about + to go over the max boundary and swap allocation + failed. + + fail + The number of times swap allocation failed either + because of running out of swap system-wide or max + limit. + Usage Guidelines ~~~~~~~~~~~~~~~~
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 85a8f00..f198339 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h@@ -54,6 +54,8 @@ enum memcg_event_item { MEMCG_HIGH, MEMCG_MAX, MEMCG_OOM, + MEMCG_SWAP_MAX, + MEMCG_SWAP_FAIL, MEMCG_NR_EVENTS, };
@@ -202,6 +204,9 @@ struct mem_cgroup { /* handle for "memory.events" */ struct cgroup_file events_file; + /* handle for "memory.swap.events" */ + struct cgroup_file swap_events_file; + /* protect arrays of thresholds */ struct mutex thresholds_lock;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9f9c8a7..1a14d4a4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c@@ -5987,13 +5987,17 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) if (!memcg) return 0; - if (!entry.val) + if (!entry.val) { + mem_cgroup_event(memcg, MEMCG_SWAP_FAIL); return 0; + } memcg = mem_cgroup_id_get_online(memcg); if (!mem_cgroup_is_root(memcg) && !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) { + mem_cgroup_event(memcg, MEMCG_SWAP_MAX); + mem_cgroup_event(memcg, MEMCG_SWAP_FAIL); mem_cgroup_id_put(memcg); return -ENOMEM; }
@@ -6131,6 +6135,18 @@ static ssize_t swap_max_write(struct kernfs_open_file *of, return nbytes; } +static int swap_events_show(struct seq_file *m, void *v) +{ + struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m)); + + memcg_stat_flush(memcg); + + seq_printf(m, "max %llu\n", memcg->events[MEMCG_SWAP_MAX]); + seq_printf(m, "fail %llu\n", memcg->events[MEMCG_SWAP_FAIL]); + + return 0; +} + static struct cftype swap_files[] = { { .name = "swap.current",
@@ -6143,6 +6159,12 @@ static struct cftype swap_files[] = { .seq_show = swap_max_show, .write = swap_max_write, }, + { + .name = "swap.events", + .flags = CFTYPE_NOT_ON_ROOT, + .file_offset = offsetof(struct mem_cgroup, swap_events_file), + .seq_show = swap_events_show, + }, { } /* terminate */ };
--
2.9.5