netdev - Re: [PATCH v6 net-next 1/5] net: add generic per-cpu page

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Message-ID: <87jzns1f71.fsf@toke.dk>
Date: Mon, 29 Jan 2024 13:45:06 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Lorenzo Bianconi <lorenzo@...nel.org>, netdev@...r.kernel.org
Cc: lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org,
 edumazet@...gle.com, pabeni@...hat.com, bpf@...r.kernel.org,
 willemdebruijn.kernel@...il.com, jasowang@...hat.com, sdf@...gle.com,
 hawk@...nel.org, ilias.apalodimas@...aro.org
Subject: Re: [PATCH v6 net-next 1/5] net: add generic per-cpu page_pool
 allocator

Lorenzo Bianconi <lorenzo@...nel.org> writes:

> Introduce generic percpu page_pools allocator.
> Moreover add page_pool_create_percpu() and cpuid filed in page_pool struct
> in order to recycle the page in the page_pool "hot" cache if
> napi_pp_put_page() is running on the same cpu.
> This is a preliminary patch to add xdp multi-buff support for xdp running
> in generic mode.
>
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> ---
>  include/net/page_pool/types.h |  3 +++
>  net/core/dev.c                | 40 +++++++++++++++++++++++++++++++++++
>  net/core/page_pool.c          | 23 ++++++++++++++++----
>  net/core/skbuff.c             |  5 +++--
>  4 files changed, 65 insertions(+), 6 deletions(-)
>
> diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
> index 76481c465375..3828396ae60c 100644
> --- a/include/net/page_pool/types.h
> +++ b/include/net/page_pool/types.h
> @@ -128,6 +128,7 @@ struct page_pool_stats {
>  struct page_pool {
>  	struct page_pool_params_fast p;
>  
> +	int cpuid;
>  	bool has_init_callback;
>  
>  	long frag_users;
> @@ -203,6 +204,8 @@ struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
>  struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset,
>  				  unsigned int size, gfp_t gfp);
>  struct page_pool *page_pool_create(const struct page_pool_params *params);
> +struct page_pool *page_pool_create_percpu(const struct page_pool_params *params,
> +					  int cpuid);
>  
>  struct xdp_mem_info;
>  
> diff --git a/net/core/dev.c b/net/core/dev.c
> index cb2dab0feee0..bf9ec740b09a 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -153,6 +153,8 @@
>  #include <linux/prandom.h>
>  #include <linux/once_lite.h>
>  #include <net/netdev_rx_queue.h>
> +#include <net/page_pool/types.h>
> +#include <net/page_pool/helpers.h>
>  
>  #include "dev.h"
>  #include "net-sysfs.h"
> @@ -442,6 +444,8 @@ static RAW_NOTIFIER_HEAD(netdev_chain);
>  DEFINE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);
>  EXPORT_PER_CPU_SYMBOL(softnet_data);
>  
> +DEFINE_PER_CPU_ALIGNED(struct page_pool *, page_pool);

I think we should come up with a better name than just "page_pool" for
this global var. In the code below it looks like it's a local variable
that's being referenced. Maybe "global_page_pool" or "system_page_pool"
or something along those lines?

-Toke