On Tue, Oct 22, 2019 at 04:44:24AM +0000, Saeed Mahameed wrote:
> From: Jonathan Lemon <jonathan.le...@gmail.com>
>
> 1) Rename functions to reflect what they are actually doing.
>
> 2) Unify the condition to keep a page.
>
> 3) When page can't be kept in cache, fallback to releasing page to page
> allocator in one place, instead of calling it from multiple conditions,
> and reuse __page_pool_return_page().
>
> Signed-off-by: Jonathan Lemon <jonathan.le...@gmail.com>
> Signed-off-by: Saeed Mahameed <sae...@mellanox.com>
> ---
> net/core/page_pool.c | 38 +++++++++++++++++++-------------------
> 1 file changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 8120aec999ce..65680aaa0818 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -258,6 +258,7 @@ static bool __page_pool_recycle_into_ring(struct
> page_pool *pool,
> struct page *page)
> {
> int ret;
> +
> /* BH protection not needed if current is serving softirq */
> if (in_serving_softirq())
> ret = ptr_ring_produce(&pool->ring, page);
> @@ -272,8 +273,8 @@ static bool __page_pool_recycle_into_ring(struct
> page_pool *pool,
> *
> * Caller must provide appropriate safe context.
> */
> -static bool __page_pool_recycle_direct(struct page *page,
> - struct page_pool *pool)
> +static bool __page_pool_recycle_into_cache(struct page *page,
> + struct page_pool *pool)
> {
> if (unlikely(pool->alloc.count == PP_ALLOC_CACHE_SIZE))
> return false;
> @@ -283,15 +284,18 @@ static bool __page_pool_recycle_direct(struct page
> *page,
> return true;
> }
>
> -/* page is NOT reusable when:
> - * 1) allocated when system is under some pressure. (page_is_pfmemalloc)
> - * 2) belongs to a different NUMA node than pool->p.nid.
> +/* Keep page in caches only if page:
> + * 1) wasn't allocated when system is under some pressure
> (page_is_pfmemalloc).
> + * 2) belongs to pool's numa node (pool->p.nid).
> + * 3) refcount is 1 (owned by page pool).
> *
> * To update pool->p.nid users must call page_pool_update_nid.
> */
> -static bool pool_page_reusable(struct page_pool *pool, struct page *page)
> +static bool page_pool_keep_page(struct page_pool *pool, struct page *page)
> {
> - return !page_is_pfmemalloc(page) && page_to_nid(page) == pool->p.nid;
> + return !page_is_pfmemalloc(page) &&
> + page_to_nid(page) == pool->p.nid &&
> + page_ref_count(page) == 1;
> }
>
> void __page_pool_put_page(struct page_pool *pool,
> @@ -300,22 +304,19 @@ void __page_pool_put_page(struct page_pool *pool,
> /* This allocator is optimized for the XDP mode that uses
> * one-frame-per-page, but have fallbacks that act like the
> * regular page allocator APIs.
> - *
> - * refcnt == 1 means page_pool owns page, and can recycle it.
> */
> - if (likely(page_ref_count(page) == 1 &&
> - pool_page_reusable(pool, page))) {
> +
> + if (likely(page_pool_keep_page(pool, page))) {
> /* Read barrier done in page_ref_count / READ_ONCE */
>
> if (allow_direct && in_serving_softirq())
> - if (__page_pool_recycle_direct(page, pool))
> + if (__page_pool_recycle_into_cache(page, pool))
> return;
>
> - if (!__page_pool_recycle_into_ring(pool, page)) {
> - /* Cache full, fallback to free pages */
> - __page_pool_return_page(pool, page);
> - }
> - return;
> + if (__page_pool_recycle_into_ring(pool, page))
> + return;
> +
> + /* Cache full, fallback to return pages */
> }
> /* Fallback/non-XDP mode: API user have elevated refcnt.
> *
> @@ -330,8 +331,7 @@ void __page_pool_put_page(struct page_pool *pool,
> * doing refcnt based recycle tricks, meaning another process
> * will be invoking put_page.
> */
> - __page_pool_clean_page(pool, page);
> - put_page(page);
> + __page_pool_return_page(pool, page);
I think Jesper had a reason for calling them separately instead of
__page_pool_return_page + put_page() (which in fact does the same thing).
In the future he was planning on removing the __page_pool_clean_page call from
there, since someone might call __page_pool_put_page() after someone has called
__page_pool_clean_page()
Can we leave the calls there as-is?
> }
> EXPORT_SYMBOL(__page_pool_put_page);
>
> --
> 2.21.0
>
Thanks
/Ilias
