On Fri, 6 Nov 2020 19:19:08 +0100 Lorenzo Bianconi <lore...@kernel.org> 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 <bro...@redhat.com> > Signed-off-by: Lorenzo Bianconi <lore...@kernel.org> > --- > include/net/page_pool.h | 26 ++++++++++++++++ > net/core/page_pool.c | 66 ++++++++++++++++++++++++++++++++++------- > net/core/xdp.c | 9 ++---- > 3 files changed, 84 insertions(+), 17 deletions(-) My own suggestion to create __page_pool_put_page() for code sharing, cause a performance regression, because compiler chooses not to inline the function. This cause unnecessary code for in_serving_softirq() and function call overhead. I'm currently testing with __always_inline and likely/unlikely annotation to get compiler to layout code better for I-cache. This shows improvements in my benchmarks. Details in[1]. [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/xdp_bulk_return01.org > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > index ef98372facf6..31dac2ad4a1f 100644 > --- a/net/core/page_pool.c > +++ b/net/core/page_pool.c [...] > @@ -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 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 is candidate for bulking */ > + return page; > } > /* Fallback/non-XDP mode: API user have elevated refcnt. > * > @@ -405,9 +405,55 @@ 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, pa_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 (!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])) > + data[pa_len++] = data[i]; > + } > + page_pool_ring_unlock(pool); > + > + /* ptr_ring cache full, free pages outside producer lock since > + * put_page() with refcnt == 1 can be an expensive operation > + */ > + for (i = 0; i < pa_len; i++) > + page_pool_return_page(pool, data[i]); > +} > +EXPORT_SYMBOL(page_pool_put_page_bulk); -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
