[PATCH v3 1/2] mm, vmstat: calculate particular vm event

Ebru Akagunduz
2016-03-14T21:40:35Z

Currently, vmstat can calculate specific vm event with all_vm_events()
however it allocates all vm events to stack. This patch introduces
a helper to sum value of a specific vm event over all cpu, without
loading all the events.

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
Changes in v2:
- this patch newly created in this version
- create sum event function to
calculate particular vm event (Kirill A. Shutemov)

Changes in v3:
- add dummy definition of sum_vm_event
when CONFIG_VM_EVENTS is not set
(Kirill A. Shutemov)

include/linux/vmstat.h | 6 ++++++
mm/vmstat.c | 12 ++++++++++++
2 files changed, 18 insertions(+)

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 73fae8c..e5ec287 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -53,6 +53,8 @@ static inline void count_vm_events(enum vm_event_item item, long delta)

extern void all_vm_events(unsigned long *);

+extern unsigned long sum_vm_event(enum vm_event_item item);
+
extern void vm_events_fold_cpu(int cpu);

#else
@@ -73,6 +75,10 @@ static inline void __count_vm_events(enum vm_event_item item, long delta)
static inline void all_vm_events(unsigned long *ret)
{
}
+static inline unsigned long sum_vm_event(enum vm_event_item item)
+{
+ return 0;
+}
static inline void vm_events_fold_cpu(int cpu)
{
}
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5e43004..b76d664 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -34,6 +34,18 @@
DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
EXPORT_PER_CPU_SYMBOL(vm_event_states);

+unsigned long sum_vm_event(enum vm_event_item item)
+{
+ int cpu;
+ unsigned long ret = 0;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu)
+ ret += per_cpu(vm_event_states, cpu).event[item];
+ put_online_cpus();
+ return ret;
+}
+
static void sum_vm_events(unsigned long *ret)
{
int cpu;
--
1.9.1