netdev - Re: [net-next v4 11/11] page_pool: Add function to batch and return stats

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Date:   Fri, 4 Feb 2022 09:46:16 +0200
From:   Ilias Apalodimas <ilias.apalodimas@...aro.org>
To:     Joe Damato <jdamato@...tly.com>
Cc:     netdev@...r.kernel.org, kuba@...nel.org, davem@...emloft.net,
        hawk@...nel.org, saeed@...nel.org, ttoukan.linux@...il.com,
        brouer@...hat.com
Subject: Re: [net-next v4 11/11] page_pool: Add function to batch and return
 stats

On Thu, Feb 03, 2022 at 04:09:33PM -0800, Joe Damato wrote:
> Adds a function page_pool_get_stats which can be used by drivers to obtain
> the batched stats for a specified page pool.
> 
> Signed-off-by: Joe Damato <jdamato@...tly.com>
> ---
>  include/net/page_pool.h |  9 +++++++++
>  net/core/page_pool.c    | 25 +++++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index bb87706..5257e46 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -153,6 +153,15 @@ struct page_pool_stats {
>  		u64 waive;  /* failed refills due to numa zone mismatch */
>  	} alloc;
>  };
> +
> +/*
> + * Drivers that wish to harvest page pool stats and report them to users
> + * (perhaps via ethtool, debugfs, or another mechanism) can allocate a
> + * struct page_pool_stats and call page_pool_get_stats to get the batched pcpu
> + * stats.
> + */
> +struct page_pool_stats *page_pool_get_stats(struct page_pool *pool,
> +					    struct page_pool_stats *stats);
>  #endif
>  
>  struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 0bd084c..076593bb 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -35,6 +35,31 @@
>  		struct page_pool_stats __percpu *s = pool->stats;	\
>  		__this_cpu_inc(s->alloc.__stat);			\
>  	} while (0)
> +
> +struct page_pool_stats *page_pool_get_stats(struct page_pool *pool,
> +					    struct page_pool_stats *stats)
> +{
> +	int cpu = 0;
> +
> +	if (!stats)
> +		return NULL;
> +
> +	for_each_possible_cpu(cpu) {
> +		const struct page_pool_stats *pcpu =
> +			per_cpu_ptr(pool->stats, cpu);
> +
> +		stats->alloc.fast += pcpu->alloc.fast;
> +		stats->alloc.slow += pcpu->alloc.slow;
> +		stats->alloc.slow_high_order +=
> +			pcpu->alloc.slow_high_order;
> +		stats->alloc.empty += pcpu->alloc.empty;
> +		stats->alloc.refill += pcpu->alloc.refill;
> +		stats->alloc.waive += pcpu->alloc.waive;
> +	}
> +
> +	return stats;
> +}
> +EXPORT_SYMBOL(page_pool_get_stats);

You don't really need to return a pointer here. Just make the return code a
bool 

Regards
/Ilias
>  #else
>  #define this_cpu_inc_alloc_stat(pool, __stat)
>  #endif
> -- 
> 2.7.4
>