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Message-ID: <20201113205904.GB1267100@apalos.home>
Date: Fri, 13 Nov 2020 22:59:04 +0200
From: Ilias Apalodimas <ilias.apalodimas@...aro.org>
To: Lorenzo Bianconi <lorenzo@...nel.org>
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org,
brouer@...hat.com, john.fastabend@...il.com
Subject: Re: [PATCH v6 net-nex 2/5] net: page_pool: add bulk support for
ptr_ring
On Fri, Nov 13, 2020 at 12:48:29PM +0100, Lorenzo Bianconi wrote:
> Introduce the capability to batch page_pool ptr_ring refill since it is
> usually run inside the driver NAPI tx completion loop.
>
> Suggested-by: Jesper Dangaard Brouer <brouer@...hat.com>
> Co-developed-by: Jesper Dangaard Brouer <brouer@...hat.com>
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> ---
> include/net/page_pool.h | 26 +++++++++++++++
> net/core/page_pool.c | 70 +++++++++++++++++++++++++++++++++++------
> net/core/xdp.c | 9 ++----
> 3 files changed, 88 insertions(+), 17 deletions(-)
>
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index 81d7773f96cd..b5b195305346 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -152,6 +152,8 @@ struct page_pool *page_pool_create(const struct page_pool_params *params);
> void page_pool_destroy(struct page_pool *pool);
> void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *));
> void page_pool_release_page(struct page_pool *pool, struct page *page);
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> + int count);
> #else
> static inline void page_pool_destroy(struct page_pool *pool)
> {
> @@ -165,6 +167,11 @@ static inline void page_pool_release_page(struct page_pool *pool,
> struct page *page)
> {
> }
> +
> +static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> + int count)
> +{
> +}
> #endif
>
> void page_pool_put_page(struct page_pool *pool, struct page *page,
> @@ -215,4 +222,23 @@ static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid)
> if (unlikely(pool->p.nid != new_nid))
> page_pool_update_nid(pool, new_nid);
> }
> +
> +static inline void page_pool_ring_lock(struct page_pool *pool)
> + __acquires(&pool->ring.producer_lock)
> +{
> + if (in_serving_softirq())
> + spin_lock(&pool->ring.producer_lock);
> + else
> + spin_lock_bh(&pool->ring.producer_lock);
> +}
> +
> +static inline void page_pool_ring_unlock(struct page_pool *pool)
> + __releases(&pool->ring.producer_lock)
> +{
> + if (in_serving_softirq())
> + spin_unlock(&pool->ring.producer_lock);
> + else
> + spin_unlock_bh(&pool->ring.producer_lock);
> +}
> +
> #endif /* _NET_PAGE_POOL_H */
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index ef98372facf6..f3c690b8c8e3 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -11,6 +11,8 @@
> #include <linux/device.h>
>
> #include <net/page_pool.h>
> +#include <net/xdp.h>
> +
> #include <linux/dma-direction.h>
> #include <linux/dma-mapping.h>
> #include <linux/page-flags.h>
> @@ -362,8 +364,9 @@ static bool pool_page_reusable(struct page_pool *pool, struct page *page)
> * If the page refcnt != 1, then the page will be returned to memory
> * subsystem.
> */
> -void page_pool_put_page(struct page_pool *pool, struct page *page,
> - unsigned int dma_sync_size, bool allow_direct)
> +static __always_inline struct page *
> +__page_pool_put_page(struct page_pool *pool, struct page *page,
> + unsigned int dma_sync_size, bool allow_direct)
> {
> /* This allocator is optimized for the XDP mode that uses
> * one-frame-per-page, but have fallbacks that act like the
> @@ -379,15 +382,12 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
> page_pool_dma_sync_for_device(pool, page,
> dma_sync_size);
>
> - if (allow_direct && in_serving_softirq())
> - if (page_pool_recycle_in_cache(page, pool))
> - return;
> + if (allow_direct && in_serving_softirq() &&
> + page_pool_recycle_in_cache(page, pool))
> + return NULL;
>
> - if (!page_pool_recycle_in_ring(pool, page)) {
> - /* Cache full, fallback to free pages */
> - page_pool_return_page(pool, page);
> - }
> - return;
> + /* Page found as candidate for recycling */
> + return page;
> }
> /* Fallback/non-XDP mode: API user have elevated refcnt.
> *
> @@ -405,9 +405,59 @@ void page_pool_put_page(struct page_pool *pool, struct page *page,
> /* Do not replace this with page_pool_return_page() */
> page_pool_release_page(pool, page);
> put_page(page);
> +
> + return NULL;
> +}
> +
> +void page_pool_put_page(struct page_pool *pool, struct page *page,
> + unsigned int dma_sync_size, bool allow_direct)
> +{
> + page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct);
> + if (page && !page_pool_recycle_in_ring(pool, page)) {
> + /* Cache full, fallback to free pages */
> + page_pool_return_page(pool, page);
> + }
> }
> EXPORT_SYMBOL(page_pool_put_page);
>
> +/* Caller must not use data area after call, as this function overwrites it */
> +void page_pool_put_page_bulk(struct page_pool *pool, void **data,
> + int count)
> +{
> + int i, bulk_len = 0;
> +
> + for (i = 0; i < count; i++) {
> + struct page *page = virt_to_head_page(data[i]);
> +
> + page = __page_pool_put_page(pool, page, -1, false);
> + /* Approved for bulk recycling in ptr_ring cache */
> + if (page)
> + data[bulk_len++] = page;
> + }
> +
> + if (unlikely(!bulk_len))
> + return;
> +
> + /* Bulk producer into ptr_ring page_pool cache */
> + page_pool_ring_lock(pool);
> + for (i = 0; i < bulk_len; i++) {
> + if (__ptr_ring_produce(&pool->ring, data[i]))
> + break; /* ring full */
> + }
> + page_pool_ring_unlock(pool);
> +
> + /* Hopefully all pages was return into ptr_ring */
> + if (likely(i == bulk_len))
> + return;
> +
> + /* ptr_ring cache full, free remaining pages outside producer lock
> + * since put_page() with refcnt == 1 can be an expensive operation
> + */
> + for (; i < bulk_len; i++)
> + page_pool_return_page(pool, data[i]);
> +}
> +EXPORT_SYMBOL(page_pool_put_page_bulk);
> +
> static void page_pool_empty_ring(struct page_pool *pool)
> {
> struct page *page;
> diff --git a/net/core/xdp.c b/net/core/xdp.c
> index bbaee7fdd44f..3d330ebda893 100644
> --- a/net/core/xdp.c
> +++ b/net/core/xdp.c
> @@ -393,16 +393,11 @@ EXPORT_SYMBOL_GPL(xdp_return_frame_rx_napi);
> void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq)
> {
> struct xdp_mem_allocator *xa = bq->xa;
> - int i;
>
> - if (unlikely(!xa))
> + if (unlikely(!xa || !bq->count))
> return;
>
> - for (i = 0; i < bq->count; i++) {
> - struct page *page = virt_to_head_page(bq->q[i]);
> -
> - page_pool_put_full_page(xa->page_pool, page, false);
> - }
> + page_pool_put_page_bulk(xa->page_pool, bq->q, bq->count);
> /* bq->xa is not cleared to save lookup, if mem.id same in next bulk */
> bq->count = 0;
> }
> --
> 2.26.2
>
Acked-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>
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