Re: [PATCH v2 1/2] mm, vmstat: calculate particular vm event

Kirill A. Shutemov
2016-03-13T23:08:19Z

On Sun, Mar 13, 2016 at 11:28:54AM +0200, Ebru Akagunduz wrote:
> 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>
> ---
> Changes in v2:
> - this patch newly created in this version
> - create sum event function to
> calculate particular vm event (Kirill A. Shutemov)
>
> include/linux/vmstat.h | 2 ++
> mm/vmstat.c | 12 ++++++++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> index 73fae8c..add0cc1 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

You need dumy definition of the function for !CONFIG_VM_EVENT_COUNTERS
case here. Otherwise build will fail. See 0-day report.

Otherwise looks good to me:

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

> 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
>
> --
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--
Kirill A. Shutemov