On 04/02/2016 06:09 AM, Waiman Long wrote:
> This patch introduces a set of simple per-cpu statictics count helper
> functions that can be used by other kernel subsystems for keeping
> track of the number of events that happens. It is per-cpu based to
> reduce overhead and improve accuracy of the counter. Using per-cpu
> counter is usually overkill for such purpose.
>
> The following APIs are provided:
>
> - int percpu_stats_init(struct percpu_stats *pcs, int num)
> Initialize the per-cpu statictics counts structure which should have
> the given number of statistics counts. Return -ENOMEM on error.
>
> - void percpu_stats_destroy(struct percpu_stats *pcs)
> Free the percpu memory allocated.
>
> - void percpu_stats_inc(struct percpu_stats *pcs, int stat)
> void percpu_stats_dec(struct percpu_stats *pcs, int stat)
> Increment and decrement the given per-cpu statistics count.
>
> - unsigned long percpu_stats_sum(struct percpu_stats *pcs, int stat)
> Return the current aggregated sum of the given statistics count.
>
> - void percpu_stats_reset(struct percpu_stats *pcs)
> Clear all the statistics counts defined in the given percpu_stats
> structure.
>
> Signed-off-by: Waiman Long <Waiman.Long@xxxxxxx>
> ---
> include/linux/percpu_stats.h | 103 ++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 103 insertions(+), 0 deletions(-)
> create mode 100644 include/linux/percpu_stats.h
Just one minor nit below.
[..]
> +static inline void
> +__percpu_stats_add(struct percpu_stats *pcs, int stat, int cnt)
> +{
> + unsigned long *pstat;
> +
> + if ((unsigned int)stat >= pcs->nstats)
> + return;
> + preempt_disable();
> + pstat = this_cpu_ptr(&pcs->stats[stat]);
> + *pstat += cnt;
> + preempt_enable();
> +}
pstat = get_cpu_ptr(&pcs->stats[stat]);
*pstat += cnt;
put_cpu_ptr(&pcs->stats[stat]);
It will generate identical code but this one uses APIs, making the
intention clearer. But as I said this is just a minor nit.
you can add my Reviewed-by: Nikolay Borisov <kernel@xxxxxxxx> for this
particular patch.
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