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Date: Mon, 4 Apr 2016 13:11:47 -0400 From: Waiman Long <waiman.long@....com> To: Nikolay Borisov <kernel@...p.com> CC: Theodore Ts'o <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca>, Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>, <linux-ext4@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Scott J Norton <scott.norton@....com>, Douglas Hatch <doug.hatch@....com>, Toshimitsu Kani <toshi.kani@....com> Subject: Re: [PATCH 2/3] percpu_stats: Simple per-cpu statistics count helper functions 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<Waiman.Long@....com> >> --- >> 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@...p.com> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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