On Wed, 24 Feb 2021 22:15:22 +0200 Ilias Apalodimas <ilias.apalodi...@linaro.org> wrote:
> 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 <bro...@redhat.com> > > [...] > > > + /* 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() I fully agree. I will fixup the code. > > + 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; > > } > > > [...] -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
