@@ -376,6 +376,10 @@ struct core_state {
struct completion startup;
};
+#ifdef CONFIG_MMAP_LOCK_HISTOGRAMS
+struct histogram_rcu;
+#endif
+
struct kioctx_table;
struct mm_struct {
struct {
@@ -437,6 +441,13 @@ struct mm_struct {
* counters
*/
struct rw_semaphore mmap_lock;
+#ifdef CONFIG_MMAP_LOCK_HISTOGRAMS
+ /* Histogram of mmap_lock contended acquire delays. kmalloc'd
+ * so we can use a forward declaration, to avoid circular
+ * dependencies between headers.
+ */
+ struct histogram_rcu *mmap_lock_contention;
+#endif
struct list_head mmlist; /* List of maybe swapped mm's. These
* are globally strung together off
@@ -817,6 +817,19 @@ config DEVICE_PRIVATE
config FRAME_VECTOR
bool
+config MMAP_LOCK_HISTOGRAMS
+ bool "mmap_lock histograms"
+ select HISTOGRAM
+ default n
+
+ help
+ Record and report latency histograms describing mmap_lock
+ contention. Stats can be read from /proc/<pid>/mmap_lock_contention.
+ True latency is only computed for *contended* acquires, to minimize
+ overhead. Uncontended acquires are recorded as having "0" latency.
+
+ If unsure, say "n".
+
config ARCH_USES_HIGH_VMA_FLAGS
bool
config ARCH_HAS_PKEYS
This histogram will be used to measure lock acquisition latency, when the acquisition is contended. Cases where we acquire the lock immediately with no contention are recorded as "0" (to avoid incurring the cost of really computing the time, while retaining the ability to get an accurate total lock acquisition count). Signed-off-by: Axel Rasmussen <axelrasmussen@google.com> --- include/linux/mm_types.h | 11 +++++++++++ mm/Kconfig | 13 +++++++++++++ 2 files changed, 24 insertions(+)