Other mechanisms for querying the peak memory usage of either a process
or v1 memory cgroup allow for resetting the high watermark. Restore
parity with those mechanisms.
For example:
- Any write to memory.max_usage_in_bytes in a cgroup v1 mount resets
the high watermark.
- writing "5" to the clear_refs pseudo-file in a processes's proc
directory resets the peak RSS.
This change copies the cgroup v1 behavior so any write to the
memory.peak and memory.swap.peak pseudo-files reset the high watermark
to the current usage.
This behavior is particularly useful for work scheduling systems that
need to track memory usage of worker processes/cgroups per-work-item.
Since memory can't be squeezed like CPU can (the OOM-killer has
opinions), these systems need to track the peak memory usage to compute
system/container fullness when binpacking workitems.
Signed-off-by: David Finkel <davidf@xxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 20 +++---
mm/memcontrol.c | 23 ++++++
.../selftests/cgroup/test_memcontrol.c | 72 ++++++++++++++++---
3 files changed, 99 insertions(+), 16 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 3f85254f3cef..95af0628dc44 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1305,11 +1305,13 @@ PAGE_SIZE multiple when read back.
reclaim induced by memory.reclaim.
memory.peak
- A read-only single value file which exists on non-root
- cgroups.
+ A read-write single value file which exists on non-root cgroups.
+
+ The max memory usage recorded for the cgroup and its descendants since
+ either the creation of the cgroup or the most recent reset.
- The max memory usage recorded for the cgroup and its
- descendants since the creation of the cgroup.
+ Any non-empty write to this file resets it to the current memory usage.
+ All content written is completely ignored.
memory.oom.group
A read-write single value file which exists on non-root
@@ -1626,11 +1628,13 @@ PAGE_SIZE multiple when read back.
Healthy workloads are not expected to reach this limit.
memory.swap.peak
- A read-only single value file which exists on non-root
- cgroups.
+ A read-write single value file which exists on non-root cgroups.
+
+ The max swap usage recorded for the cgroup and its descendants since
+ the creation of the cgroup or the most recent reset.
- The max swap usage recorded for the cgroup and its
- descendants since the creation of the cgroup.
+ Any non-empty write to this file resets it to the current swap usage.
+ All content written is completely ignored.
memory.swap.max
A read-write single value file which exists on non-root
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1c1061df9cd1..b04af158922d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -25,6 +25,7 @@
* Copyright (C) 2020 Alibaba, Inc, Alex Shi
*/
+#include <linux/cgroup-defs.h>
#include <linux/page_counter.h>
#include <linux/memcontrol.h>
#include <linux/cgroup.h>
@@ -6635,6 +6636,16 @@ static u64 memory_peak_read(struct cgroup_subsys_state *css,
return (u64)memcg->memory.watermark * PAGE_SIZE;
}
+static ssize_t memory_peak_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+ page_counter_reset_watermark(&memcg->memory);
+
+ return nbytes;
+}
+
static int memory_min_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
@@ -6947,6 +6958,7 @@ static struct cftype memory_files[] = {
.name = "peak",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = memory_peak_read,
+ .write = memory_peak_write,
},
{
.name = "min",
@@ -7917,6 +7929,16 @@ static u64 swap_peak_read(struct cgroup_subsys_state *css,
return (u64)memcg->swap.watermark * PAGE_SIZE;
}
+static ssize_t swap_peak_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+ page_counter_reset_watermark(&memcg->swap);
+
+ return nbytes;
+}
+
static int swap_high_show(struct seq_file *m, void *v)
{
return seq_puts_memcg_tunable(m,
@@ -7999,6 +8021,7 @@ static struct cftype swap_files[] = {
.name = "swap.peak",
.flags = CFTYPE_NOT_ON_ROOT,
.read_u64 = swap_peak_read,
+ .write = swap_peak_write,
},
{
.name = "swap.events",
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index c7c9572003a8..0326c317f1f2 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -161,12 +161,12 @@ static int alloc_pagecache_50M_check(const char *cgroup, void *arg)
/*
* This test create a memory cgroup, allocates
* some anonymous memory and some pagecache
- * and check memory.current and some memory.stat values.
+ * and checks memory.current, memory.peak, and some memory.stat values.
*/
-static int test_memcg_current(const char *root)
+static int test_memcg_current_peak(const char *root)
{
int ret = KSFT_FAIL;
- long current;
+ long current, peak, peak_reset;
char *memcg;
memcg = cg_name(root, "memcg_test");
@@ -180,12 +180,32 @@ static int test_memcg_current(const char *root)
if (current != 0)
goto cleanup;
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak != 0)
+ goto cleanup;
+
if (cg_run(memcg, alloc_anon_50M_check, NULL))
goto cleanup;
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak < MB(50))
+ goto cleanup;
+
+ peak_reset = cg_write(memcg, "memory.peak", "\n");
+ if (peak_reset != 0)
+ goto cleanup;
+
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak > MB(30))
+ goto cleanup;
+
if (cg_run(memcg, alloc_pagecache_50M_check, NULL))
goto cleanup;
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak < MB(50))
+ goto cleanup;
+
ret = KSFT_PASS;
cleanup:
@@ -815,13 +835,14 @@ static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)
/*
* This test checks that memory.swap.max limits the amount of
- * anonymous memory which can be swapped out.
+ * anonymous memory which can be swapped out. Additionally, it verifies that
+ * memory.swap.peak reflects the high watermark and can be reset.
*/
-static int test_memcg_swap_max(const char *root)
+static int test_memcg_swap_max_peak(const char *root)
{
int ret = KSFT_FAIL;
char *memcg;
- long max;
+ long max, peak;
if (!is_swap_enabled())
return KSFT_SKIP;
@@ -838,6 +859,12 @@ static int test_memcg_swap_max(const char *root)
goto cleanup;
}
+ if (cg_read_long(memcg, "memory.swap.peak"))
+ goto cleanup;
+
+ if (cg_read_long(memcg, "memory.peak"))
+ goto cleanup;
+
if (cg_read_strcmp(memcg, "memory.max", "max\n"))
goto cleanup;
@@ -860,6 +887,27 @@ static int test_memcg_swap_max(const char *root)
if (cg_read_key_long(memcg, "memory.events", "oom_kill ") != 1)
goto cleanup;
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak < MB(29))
+ goto cleanup;
+
+ peak = cg_read_long(memcg, "memory.swap.peak");
+ if (peak < MB(29))
+ goto cleanup;
+
+ if (cg_write(memcg, "memory.swap.peak", "\n"))
+ goto cleanup;
+
+ if (cg_read_long(memcg, "memory.swap.peak") > MB(10))
+ goto cleanup;
+
+
+ if (cg_write(memcg, "memory.peak", "\n"))
+ goto cleanup;
+
+ if (cg_read_long(memcg, "memory.peak"))
+ goto cleanup;
+
if (cg_run(memcg, alloc_anon_50M_check_swap, (void *)MB(30)))
goto cleanup;
@@ -867,6 +915,14 @@ static int test_memcg_swap_max(const char *root)
if (max <= 0)
goto cleanup;
+ peak = cg_read_long(memcg, "memory.peak");
+ if (peak < MB(29))
+ goto cleanup;
+
+ peak = cg_read_long(memcg, "memory.swap.peak");
+ if (peak < MB(19))
+ goto cleanup;
+
ret = KSFT_PASS;
cleanup:
@@ -1293,7 +1349,7 @@ struct memcg_test {
const char *name;
} tests[] = {
T(test_memcg_subtree_control),
- T(test_memcg_current),
+ T(test_memcg_current_peak),
T(test_memcg_min),
T(test_memcg_low),
T(test_memcg_high),
@@ -1301,7 +1357,7 @@ struct memcg_test {
T(test_memcg_max),
T(test_memcg_reclaim),
T(test_memcg_oom_events),
- T(test_memcg_swap_max),
+ T(test_memcg_swap_max_peak),
T(test_memcg_sock),
T(test_memcg_oom_group_leaf_events),
T(test_memcg_oom_group_parent_events),
--
2.39.2
