From 8610037e8106b48c79cfe0afb92b2b2466e51c3d Mon Sep 17 00:00:00 2001 From: Joe Damato Date: Tue, 1 Mar 2022 23:55:47 -0800 Subject: [PATCH] page_pool: Add allocation stats Add per-pool statistics counters for the allocation path of a page pool. These stats are incremented in softirq context, so no locking or per-cpu variables are needed. This code is disabled by default and a kernel config option is provided for users who wish to enable them. The statistics added are: - fast: successful fast path allocations - slow: slow path order-0 allocations - slow_high_order: slow path high order allocations - empty: ptr ring is empty, so a slow path allocation was forced. - refill: an allocation which triggered a refill of the cache - waive: pages obtained from the ptr ring that cannot be added to the cache due to a NUMA mismatch. Signed-off-by: Joe Damato Acked-by: Jesper Dangaard Brouer Reviewed-by: Ilias Apalodimas Signed-off-by: David S. Miller --- include/net/page_pool.h | 18 ++++++++++++++++++ net/Kconfig | 13 +++++++++++++ net/core/page_pool.c | 24 ++++++++++++++++++++---- 3 files changed, 51 insertions(+), 4 deletions(-) --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -82,6 +82,19 @@ struct page_pool_params { unsigned int offset; /* DMA addr offset */ }; +#ifdef CONFIG_PAGE_POOL_STATS +struct page_pool_alloc_stats { + u64 fast; /* fast path allocations */ + u64 slow; /* slow-path order 0 allocations */ + u64 slow_high_order; /* slow-path high order allocations */ + u64 empty; /* failed refills due to empty ptr ring, forcing + * slow path allocation + */ + u64 refill; /* allocations via successful refill */ + u64 waive; /* failed refills due to numa zone mismatch */ +}; +#endif + struct page_pool { struct page_pool_params p; @@ -132,6 +145,11 @@ struct page_pool { refcount_t user_cnt; u64 destroy_cnt; + +#ifdef CONFIG_PAGE_POOL_STATS + /* these stats are incremented while in softirq context */ + struct page_pool_alloc_stats alloc_stats; +#endif }; struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); --- a/net/Kconfig +++ b/net/Kconfig @@ -432,6 +432,19 @@ config NET_DEVLINK config PAGE_POOL bool +config PAGE_POOL_STATS + default n + bool "Page pool stats" + depends on PAGE_POOL + help + Enable page pool statistics to track page allocation and recycling + in page pools. This option incurs additional CPU cost in allocation + and recycle paths and additional memory cost to store the statistics. + These statistics are only available if this option is enabled and if + the driver using the page pool supports exporting this data. + + If unsure, say N. + config FAILOVER tristate "Generic failover module" help --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -49,6 +49,13 @@ static void page_pool_producer_unlock(st spin_unlock_bh(&pool->ring.producer_lock); } +#ifdef CONFIG_PAGE_POOL_STATS +/* alloc_stat_inc is intended to be used in softirq context */ +#define alloc_stat_inc(pool, __stat) (pool->alloc_stats.__stat++) +#else +#define alloc_stat_inc(pool, __stat) +#endif + static int page_pool_init(struct page_pool *pool, const struct page_pool_params *params) { @@ -140,8 +147,10 @@ static struct page *page_pool_refill_all int pref_nid; /* preferred NUMA node */ /* Quicker fallback, avoid locks when ring is empty */ - if (__ptr_ring_empty(r)) + if (__ptr_ring_empty(r)) { + alloc_stat_inc(pool, empty); return NULL; + } /* Softirq guarantee CPU and thus NUMA node is stable. This, * assumes CPU refilling driver RX-ring will also run RX-NAPI. @@ -171,14 +180,17 @@ static struct page *page_pool_refill_all * This limit stress on page buddy alloactor. */ page_pool_return_page(pool, page); + alloc_stat_inc(pool, waive); page = NULL; break; } } while (pool->alloc.count < PP_ALLOC_CACHE_REFILL); /* Return last page */ - if (likely(pool->alloc.count > 0)) + if (likely(pool->alloc.count > 0)) { page = pool->alloc.cache[--pool->alloc.count]; + alloc_stat_inc(pool, refill); + } spin_unlock(&r->consumer_lock); return page; @@ -193,6 +205,7 @@ static struct page *__page_pool_get_cach if (likely(pool->alloc.count)) { /* Fast-path */ page = pool->alloc.cache[--pool->alloc.count]; + alloc_stat_inc(pool, fast); } else { page = page_pool_refill_alloc_cache(pool); } @@ -264,6 +277,7 @@ static struct page *__page_pool_alloc_pa return NULL; } + alloc_stat_inc(pool, slow_high_order); page_pool_set_pp_info(pool, page); /* Track how many pages are held 'in-flight' */ @@ -318,10 +332,12 @@ static struct page *__page_pool_alloc_pa } /* Return last page */ - if (likely(pool->alloc.count > 0)) + if (likely(pool->alloc.count > 0)) { page = pool->alloc.cache[--pool->alloc.count]; - else + alloc_stat_inc(pool, slow); + } else { page = NULL; + } /* When page just alloc'ed is should/must have refcnt 1. */ return page;