Hi Jesper, On Wed, Feb 24, 2021 at 07:56:46PM +0100, Jesper Dangaard Brouer wrote: > There are cases where the page_pool need to refill with pages from the > page allocator. Some workloads cause the page_pool to release pages > instead of recycling these pages. > > For these workload it can improve performance to bulk alloc pages from > the page-allocator to refill the alloc cache. > > For XDP-redirect workload with 100G mlx5 driver (that use page_pool) > redirecting xdp_frame packets into a veth, that does XDP_PASS to create > an SKB from the xdp_frame, which then cannot return the page to the > page_pool. In this case, we saw[1] an improvement of 18.8% from using > the alloc_pages_bulk API (3,677,958 pps -> 4,368,926 pps). > > [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool06_alloc_pages_bulk.org > > Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> [...] > + /* Remaining pages store in alloc.cache */ > + list_for_each_entry_safe(page, next, &page_list, lru) { > + list_del(&page->lru); > + if (pp_flags & PP_FLAG_DMA_MAP) { > + page = page_pool_dma_map(pool, page); > + if (!page) As I commented on the previous patch, i'd prefer the put_page() here to be explicitly called, instead of hiding in the page_pool_dma_map() > + continue; > + } > + if (likely(pool->alloc.count < PP_ALLOC_CACHE_SIZE)) { > + pool->alloc.cache[pool->alloc.count++] = page; > + pool->pages_state_hold_cnt++; > + trace_page_pool_state_hold(pool, page, > + pool->pages_state_hold_cnt); > + } else { > + put_page(page); > + } > + } > +out: > if (pool->p.flags & PP_FLAG_DMA_MAP) { > - page = page_pool_dma_map(pool, page); > - if (!page) > + first_page = page_pool_dma_map(pool, first_page); > + if (!first_page) > return NULL; > } > [...] Cheers /Ilias
