The show method of /sys/kernel/slab/<slab>/shrink sysfs file currently
returns nothing. This is now modified to show the time of the last
cache shrink operation in us.
CONFIG_SLUB_DEBUG depends on CONFIG_SYSFS. So the new shrink_us field
is always available to the shrink methods.
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-kernel-slab | 2 ++
include/linux/slub_def.h | 1 +
mm/slub.c | 12 +++++++++---
3 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab
index 94ffd47fc8d7..9869a3f57dc3 100644
--- a/Documentation/ABI/testing/sysfs-kernel-slab
+++ b/Documentation/ABI/testing/sysfs-kernel-slab
@@ -437,6 +437,8 @@ Description:
write for shrinking the cache. Other input values are
considered invalid. If it is a root cache, all the
child memcg caches will also be shrunk, if available.
+ When read, the time in us of the last cache shrink
+ operation is shown.
What: /sys/kernel/slab/cache/slab_size
Date: May 2007
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index d2153789bd9f..055474197e83 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -113,6 +113,7 @@ struct kmem_cache {
/* For propagation, maximum size of a stored attr */
unsigned int max_attr_size;
#ifdef CONFIG_SYSFS
+ unsigned int shrink_us; /* Cache shrink time in us */
struct kset *memcg_kset;
#endif
#endif
diff --git a/mm/slub.c b/mm/slub.c
index 9736eb10dcb8..77d67a55ce43 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -34,6 +34,7 @@
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
#include <linux/random.h>
+#include <linux/sched/clock.h>
#include <trace/events/kmem.h>
@@ -5287,16 +5288,21 @@ SLAB_ATTR(failslab);
static ssize_t shrink_show(struct kmem_cache *s, char *buf)
{
- return 0;
+ return sprintf(buf, "%u\n", s->shrink_us);
}
static ssize_t shrink_store(struct kmem_cache *s,
const char *buf, size_t length)
{
- if (buf[0] == '1')
+ if (buf[0] == '1') {
+ u64 start = sched_clock();
+
kmem_cache_shrink_all(s);
- else
+ s->shrink_us = (unsigned int)div_u64(sched_clock() - start,
+ NSEC_PER_USEC);
+ } else {
return -EINVAL;
+ }
return length;
}
SLAB_ATTR(shrink);
--
2.18.1
