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authorJesper Dangaard Brouer <brouer@redhat.com>2021-04-30 09:02:07 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 21:20:43 +0300
commitbe5dba25b4b27f262626ddc9079d4858a75462fd (patch)
treeb3ee882a42ac89449805d0b716b3761d29808662 /net
parentdfa59717b97d4203e6b44ee82874d4f758d93542 (diff)
downloadlinux-be5dba25b4b27f262626ddc9079d4858a75462fd.tar.xz
net: page_pool: use alloc_pages_bulk in refill code path
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. Performance results under GitHub xdp-project[1]: [1] https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool06_alloc_pages_bulk.org Mel: The patch "net: page_pool: convert to use alloc_pages_bulk_array variant" was squashed with this patch. From the test page, the array variant was superior with one of the test results as follows. Kernel XDP stats CPU pps Delta Baseline XDP-RX CPU total 3,771,046 n/a List XDP-RX CPU total 3,940,242 +4.49% Array XDP-RX CPU total 4,249,224 +12.68% Link: https://lkml.kernel.org/r/20210325114228.27719-10-mgorman@techsingularity.net Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chuck Lever <chuck.lever@oracle.com> Cc: David Miller <davem@davemloft.net> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/core/page_pool.c82
1 files changed, 56 insertions, 26 deletions
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 40e1b2beaa6c..9ec1aa9640ad 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -203,38 +203,17 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
return true;
}
-/* slow path */
-noinline
-static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
- gfp_t _gfp)
+static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
+ gfp_t gfp)
{
- unsigned int pp_flags = pool->p.flags;
struct page *page;
- 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)
- gfp |= __GFP_COMP;
-
- /* 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
+ gfp |= __GFP_COMP;
page = alloc_pages_node(pool->p.nid, gfp, pool->p.order);
-#else
- page = alloc_pages(gfp, pool->p.order);
-#endif
- if (!page)
+ if (unlikely(!page))
return NULL;
- if ((pp_flags & PP_FLAG_DMA_MAP) &&
+ if ((pool->p.flags & PP_FLAG_DMA_MAP) &&
unlikely(!page_pool_dma_map(pool, page))) {
put_page(page);
return NULL;
@@ -243,6 +222,57 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
/* 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);
+ return page;
+}
+
+/* slow path */
+noinline
+static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
+ gfp_t gfp)
+{
+ const int bulk = PP_ALLOC_CACHE_REFILL;
+ unsigned int pp_flags = pool->p.flags;
+ unsigned int pp_order = pool->p.order;
+ struct page *page;
+ int i, nr_pages;
+
+ /* Don't support bulk alloc for high-order pages */
+ if (unlikely(pp_order))
+ return __page_pool_alloc_page_order(pool, gfp);
+
+ /* Unnecessary as alloc cache is empty, but guarantees zero count */
+ if (unlikely(pool->alloc.count > 0))
+ return pool->alloc.cache[--pool->alloc.count];
+
+ /* Mark empty alloc.cache slots "empty" for alloc_pages_bulk_array */
+ memset(&pool->alloc.cache, 0, sizeof(void *) * bulk);
+
+ nr_pages = alloc_pages_bulk_array(gfp, bulk, pool->alloc.cache);
+ if (unlikely(!nr_pages))
+ return NULL;
+
+ /* Pages have been filled into alloc.cache array, but count is zero and
+ * page element have not been (possibly) DMA mapped.
+ */
+ for (i = 0; i < nr_pages; i++) {
+ page = pool->alloc.cache[i];
+ if ((pp_flags & PP_FLAG_DMA_MAP) &&
+ unlikely(!page_pool_dma_map(pool, page))) {
+ put_page(page);
+ continue;
+ }
+ pool->alloc.cache[pool->alloc.count++] = page;
+ /* 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);
+ }
+
+ /* Return last page */
+ if (likely(pool->alloc.count > 0))
+ page = pool->alloc.cache[--pool->alloc.count];
+ else
+ page = NULL;
/* When page just alloc'ed is should/must have refcnt 1. */
return page;