The patch titled
Subject: mm, memcontrol: implement memory.swap.events
has been added to the -mm tree. Its filename is
mm-memcontrol-implement-memoryswapevents.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcontrol-implement-memoryswapevents.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcontrol-implement-memoryswapevents.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Tejun Heo <tj@xxxxxxxxxx>
Subject: mm, memcontrol: implement memory.swap.events
Add swap max and fail events so that userland can monitor and respond to
running out of swap.
I'm not too sure about the fail event. Right now, it's a bit confusing
which stats / events are recursive and which aren't and also which ones
reflect events which originate from a given cgroup and which targets the
cgroup. No idea what the right long term solution is and it could just be
that growing them organically is actually the only right thing to do.
Link: http://lkml.kernel.org/r/20180416231151.GI1911913@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: <linux-api@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cgroup-v2.txt | 16 ++++++++++++++++
include/linux/memcontrol.h | 5 +++++
mm/memcontrol.c | 24 +++++++++++++++++++++++-
3 files changed, 44 insertions(+), 1 deletion(-)
diff -puN Documentation/cgroup-v2.txt~mm-memcontrol-implement-memoryswapevents Documentation/cgroup-v2.txt
--- a/Documentation/cgroup-v2.txt~mm-memcontrol-implement-memoryswapevents
+++ a/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 -puN include/linux/memcontrol.h~mm-memcontrol-implement-memoryswapevents include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~mm-memcontrol-implement-memoryswapevents
+++ a/include/linux/memcontrol.h
@@ -53,6 +53,8 @@ enum memcg_memory_event {
MEMCG_HIGH,
MEMCG_MAX,
MEMCG_OOM,
+ MEMCG_SWAP_MAX,
+ MEMCG_SWAP_FAIL,
MEMCG_NR_MEMORY_EVENTS,
};
@@ -208,6 +210,9 @@ struct mem_cgroup {
atomic_long_t memory_events[MEMCG_NR_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 -puN mm/memcontrol.c~mm-memcontrol-implement-memoryswapevents mm/memcontrol.c
--- a/mm/memcontrol.c~mm-memcontrol-implement-memoryswapevents
+++ a/mm/memcontrol.c
@@ -6019,13 +6019,17 @@ int mem_cgroup_try_charge_swap(struct pa
if (!memcg)
return 0;
- if (!entry.val)
+ if (!entry.val) {
+ memcg_memory_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)) {
+ memcg_memory_event(memcg, MEMCG_SWAP_MAX);
+ memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
mem_cgroup_id_put(memcg);
return -ENOMEM;
}
@@ -6163,6 +6167,18 @@ static ssize_t swap_max_write(struct ker
return nbytes;
}
+static int swap_events_show(struct seq_file *m, void *v)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+ seq_printf(m, "max %lu\n",
+ atomic_long_read(&memcg->memory_events[MEMCG_SWAP_MAX]));
+ seq_printf(m, "fail %lu\n",
+ atomic_long_read(&memcg->memory_events[MEMCG_SWAP_FAIL]));
+
+ return 0;
+}
+
static struct cftype swap_files[] = {
{
.name = "swap.current",
@@ -6175,6 +6191,12 @@ 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 */
};
_
Patches currently in -mm which might be from tj@xxxxxxxxxx are
mm-memcontrol-move-swap-charge-handling-into-get_swap_page.patch
mm-memcontrol-implement-memoryswapevents.patch
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