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 <[email protected]>
---
net/core/page_pool.c | 63 ++++++++++++++++++++++++++++++++------------------
1 file changed, 40 insertions(+), 23 deletions(-)
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index a26f2ceb6a87..567680bd91c4 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -208,44 +208,61 @@ noinline
static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
gfp_t _gfp)
{
+ const int bulk = PP_ALLOC_CACHE_REFILL;
+ struct page *page, *next, *first_page;
unsigned int pp_flags = pool->p.flags;
- struct page *page;
+ unsigned int pp_order = pool->p.order;
+ int pp_nid = pool->p.nid;
+ LIST_HEAD(page_list);
gfp_t gfp = _gfp;
- /* We could always set __GFP_COMP, and avoid this branch, as
- * prep_new_page() can handle order-0 with __GFP_COMP.
- */
- if (pool->p.order)
+ /* Don't support bulk alloc for high-order pages */
+ if (unlikely(pp_order)) {
gfp |= __GFP_COMP;
+ first_page = alloc_pages_node(pp_nid, gfp, pp_order);
+ if (unlikely(!first_page))
+ return NULL;
+ goto out;
+ }
- /* FUTURE development:
- *
- * Current slow-path essentially falls back to single page
- * allocations, which doesn't improve performance. This code
- * need bulk allocation support from the page allocator code.
- */
-
- /* Cache was empty, do real allocation */
-#ifdef CONFIG_NUMA
- page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
-#else
- page = alloc_pages(gfp, pool->p.order);
-#endif
- if (!page)
+ if (unlikely(!__alloc_pages_bulk_nodemask(gfp, pp_nid, NULL,
+ bulk, &page_list)))
return NULL;
+ /* First page is extracted and returned to caller */
+ first_page = list_first_entry(&page_list, struct page, lru);
+ list_del(&first_page->lru);
+
+ /* 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 &&
+ unlikely(!page_pool_dma_map(pool, page))) {
+ put_page(page);
+ 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 (pp_flags & PP_FLAG_DMA_MAP &&
- unlikely(!page_pool_dma_map(pool, page))) {
- put_page(page);
+ unlikely(!page_pool_dma_map(pool, first_page))) {
+ put_page(first_page);
return NULL;
}
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
- trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
+ trace_page_pool_state_hold(pool, first_page, pool->pages_state_hold_cnt);
/* When page just alloc'ed is should/must have refcnt 1. */
- return page;
+ return first_page;
}
/* For using page_pool replace: alloc_pages() API calls, but provide