netdev - Re: [net-next v7 1/4] page_pool: Add allocation stats

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Date:   Mon, 28 Feb 2022 08:07:01 +0100
From:   Jesper Dangaard Brouer <jbrouer@...hat.com>
To:     Joe Damato <jdamato@...tly.com>, netdev@...r.kernel.org,
        kuba@...nel.org, ilias.apalodimas@...aro.org, davem@...emloft.net,
        hawk@...nel.org, saeed@...nel.org, ttoukan.linux@...il.com
Cc:     brouer@...hat.com
Subject: Re: [net-next v7 1/4] page_pool: Add allocation stats


On 25/02/2022 18.41, Joe Damato wrote:
> Add per-pool statistics counters for the allocation path of a page pool.
> These stats are incremented in softirq context, so no locking or per-cpu
> variables are needed.
> 
> This code is disabled by default and a kernel config option is provided for
> users who wish to enable them.
> 
> The statistics added are:
> 	- fast: successful fast path allocations
> 	- slow: slow path order-0 allocations
> 	- slow_high_order: slow path high order allocations
> 	- empty: ptr ring is empty, so a slow path allocation was forced.
> 	- refill: an allocation which triggered a refill of the cache
> 	- waive: pages obtained from the ptr ring that cannot be added to
> 	  the cache due to a NUMA mismatch.
> 
> Signed-off-by: Joe Damato<jdamato@...tly.com>
> ---
>   include/net/page_pool.h | 18 ++++++++++++++++++
>   net/Kconfig             | 13 +++++++++++++
>   net/core/page_pool.c    | 24 ++++++++++++++++++++----
>   3 files changed, 51 insertions(+), 4 deletions(-)
> 
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index 97c3c19..1f27e8a4 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -84,6 +84,19 @@ struct page_pool_params {
>   	void *init_arg;
>   };
>   
> +#ifdef CONFIG_PAGE_POOL_STATS
> +struct page_pool_alloc_stats {
> +	u64 fast; /* fast path allocations */
> +	u64 slow; /* slow-path order 0 allocations */
> +	u64 slow_high_order; /* slow-path high order allocations */
> +	u64 empty; /* failed refills due to empty ptr ring, forcing
> +		    * slow path allocation
> +		    */
> +	u64 refill; /* allocations via successful refill */
> +	u64 waive;  /* failed refills due to numa zone mismatch */
> +};
> +#endif
> +
>   struct page_pool {
>   	struct page_pool_params p;
>   
> @@ -96,6 +109,11 @@ struct page_pool {
>   	unsigned int frag_offset;
>   	struct page *frag_page;
>   	long frag_users;
> +
> +#ifdef CONFIG_PAGE_POOL_STATS
> +	/* these stats are incremented while in softirq context */
> +	struct page_pool_alloc_stats alloc_stats;
> +#endif
>   	u32 xdp_mem_id;

I like the cache-line placement.

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>