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 <[email protected]> Suggested-by: Kirill A. Shutemov <[email protected]> Acked-by: Kirill A. Shutemov <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Acked-by: Vlastimil Babka <[email protected]> --- 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) Changes in v4: - add Suggested-by tag (Vlastimil Babka) Changes in v5: - CC'ed Christoph Lameter <[email protected]> (Andrew Morton) 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 9e07d11..1d5d89e 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
