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Message-Id: <1645574424-60857-2-git-send-email-jdamato@fastly.com>
Date: Tue, 22 Feb 2022 16:00:23 -0800
From: Joe Damato <jdamato@...tly.com>
To: netdev@...r.kernel.org, kuba@...nel.org,
ilias.apalodimas@...aro.org, davem@...emloft.net, hawk@...nel.org,
saeed@...nel.org, ttoukan.linux@...il.com, brouer@...hat.com
Cc: Joe Damato <jdamato@...tly.com>
Subject: [net-next v6 1/2] page_pool: Add page_pool stats
Add per-cpu per-pool statistics counters for the allocation path of a page
pool.
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 <jdamato@...tly.com>
---
include/net/page_pool.h | 18 ++++++++++++++++++
net/Kconfig | 13 +++++++++++++
net/core/page_pool.c | 37 +++++++++++++++++++++++++++++++++----
3 files changed, 64 insertions(+), 4 deletions(-)
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 97c3c19..bedc82f 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -135,7 +135,25 @@ struct page_pool {
refcount_t user_cnt;
u64 destroy_cnt;
+#ifdef CONFIG_PAGE_POOL_STATS
+ struct page_pool_stats __percpu *stats ____cacheline_aligned_in_smp;
+#endif
+};
+
+#ifdef CONFIG_PAGE_POOL_STATS
+struct page_pool_stats {
+ struct {
+ 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 */
+ } alloc;
};
+#endif
struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
diff --git a/net/Kconfig b/net/Kconfig
index 8a1f9d0..8c07308 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -434,6 +434,19 @@ 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 allocations. This option
+ incurs additional CPU cost in allocation 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
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index e25d359..f29dff9 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -26,6 +26,17 @@
#define BIAS_MAX LONG_MAX
+#ifdef CONFIG_PAGE_POOL_STATS
+/* this_cpu_inc_alloc_stat is intended to be used in softirq context */
+#define this_cpu_inc_alloc_stat(pool, __stat) \
+ do { \
+ struct page_pool_stats __percpu *s = pool->stats; \
+ __this_cpu_inc(s->alloc.__stat); \
+ } while (0)
+#else
+#define this_cpu_inc_alloc_stat(pool, __stat)
+#endif
+
static int page_pool_init(struct page_pool *pool,
const struct page_pool_params *params)
{
@@ -73,6 +84,12 @@ static int page_pool_init(struct page_pool *pool,
pool->p.flags & PP_FLAG_PAGE_FRAG)
return -EINVAL;
+#ifdef CONFIG_PAGE_POOL_STATS
+ pool->stats = alloc_percpu(struct page_pool_stats);
+ if (!pool->stats)
+ return -ENOMEM;
+#endif
+
if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
return -ENOMEM;
@@ -117,8 +134,10 @@ static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
int pref_nid; /* preferred NUMA node */
/* Quicker fallback, avoid locks when ring is empty */
- if (__ptr_ring_empty(r))
+ if (__ptr_ring_empty(r)) {
+ this_cpu_inc_alloc_stat(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.
@@ -145,14 +164,17 @@ static struct page *page_pool_refill_alloc_cache(struct page_pool *pool)
* This limit stress on page buddy alloactor.
*/
page_pool_return_page(pool, page);
+ this_cpu_inc_alloc_stat(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];
+ this_cpu_inc_alloc_stat(pool, refill);
+ }
return page;
}
@@ -166,6 +188,7 @@ static struct page *__page_pool_get_cached(struct page_pool *pool)
if (likely(pool->alloc.count)) {
/* Fast-path */
page = pool->alloc.cache[--pool->alloc.count];
+ this_cpu_inc_alloc_stat(pool, fast);
} else {
page = page_pool_refill_alloc_cache(pool);
}
@@ -239,6 +262,7 @@ static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
return NULL;
}
+ this_cpu_inc_alloc_stat(pool, slow_high_order);
page_pool_set_pp_info(pool, page);
/* Track how many pages are held 'in-flight' */
@@ -293,10 +317,12 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
}
/* Return last page */
- if (likely(pool->alloc.count > 0))
+ if (likely(pool->alloc.count > 0)) {
page = pool->alloc.cache[--pool->alloc.count];
- else
+ this_cpu_inc_alloc_stat(pool, slow);
+ } else {
page = NULL;
+ }
/* When page just alloc'ed is should/must have refcnt 1. */
return page;
@@ -620,6 +646,9 @@ static void page_pool_free(struct page_pool *pool)
if (pool->p.flags & PP_FLAG_DMA_MAP)
put_device(pool->p.dev);
+#ifdef CONFIG_PAGE_POOL_STATS
+ free_percpu(pool->stats);
+#endif
kfree(pool);
}
--
2.7.4
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