From d5394610b1ba06373b3543b5177a4c91052f9f62 Mon Sep 17 00:00:00 2001 From: Saeed Mahameed Date: Wed, 20 Nov 2019 00:15:19 +0000 Subject: [PATCH] page_pool: Don't recycle non-reusable pages A page is NOT reusable when at least one of the following is true: 1) allocated when system was under some pressure. (page_is_pfmemalloc) 2) belongs to a different NUMA node than pool->p.nid. To update pool->p.nid users should call page_pool_update_nid(). Holding on to such pages in the pool will hurt the consumer performance when the pool migrates to a different numa node. Performance testing: XDP drop/tx rate and TCP single/multi stream, on mlx5 driver while migrating rx ring irq from close to far numa: mlx5 internal page cache was locally disabled to get pure page pool results. CPU: Intel(R) Xeon(R) CPU E5-2603 v4 @ 1.70GHz NIC: Mellanox Technologies MT27700 Family [ConnectX-4] (100G) XDP Drop/TX single core: NUMA | XDP | Before | After --------------------------------------- Close | Drop | 11 Mpps | 10.9 Mpps Far | Drop | 4.4 Mpps | 5.8 Mpps Close | TX | 6.5 Mpps | 6.5 Mpps Far | TX | 3.5 Mpps | 4 Mpps Improvement is about 30% drop packet rate, 15% tx packet rate for numa far test. No degradation for numa close tests. TCP single/multi cpu/stream: NUMA | #cpu | Before | After -------------------------------------- Close | 1 | 18 Gbps | 18 Gbps Far | 1 | 15 Gbps | 18 Gbps Close | 12 | 80 Gbps | 80 Gbps Far | 12 | 68 Gbps | 80 Gbps In all test cases we see improvement for the far numa case, and no impact on the close numa case. The impact of adding a check per page is very negligible, and shows no performance degradation whatsoever, also functionality wise it seems more correct and more robust for page pool to verify when pages should be recycled, since page pool can't guarantee where pages are coming from. Signed-off-by: Saeed Mahameed Acked-by: Jonathan Lemon Reviewed-by: Ilias Apalodimas Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- net/core/page_pool.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 9b704ea3f4b2..6c7f78bd6421 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -281,6 +281,17 @@ static bool __page_pool_recycle_direct(struct page *page, return true; } +/* page is NOT reusable when: + * 1) allocated when system is under some pressure. (page_is_pfmemalloc) + * 2) belongs to a different NUMA node than pool->p.nid. + * + * To update pool->p.nid users must call page_pool_update_nid. + */ +static bool pool_page_reusable(struct page_pool *pool, struct page *page) +{ + return !page_is_pfmemalloc(page) && page_to_nid(page) == pool->p.nid; +} + void __page_pool_put_page(struct page_pool *pool, struct page *page, bool allow_direct) { @@ -290,7 +301,8 @@ void __page_pool_put_page(struct page_pool *pool, * * refcnt == 1 means page_pool owns page, and can recycle it. */ - if (likely(page_ref_count(page) == 1)) { + if (likely(page_ref_count(page) == 1 && + pool_page_reusable(pool, page))) { /* Read barrier done in page_ref_count / READ_ONCE */ if (allow_direct && in_serving_softirq())