On 04/04/2016 03:36 AM, Nikolay Borisov wrote:
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<[email protected]> --- include/linux/percpu_stats.h | 103 ++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 103 insertions(+), 0 deletions(-) create mode 100644 include/linux/percpu_stats.hJust 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<[email protected]> for this particular patch.
Yes, that will certainly make it look nicer. I will update the patch once I get feedback from my other ext4 patches.
Cheers, Longman
