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Diffstat (limited to 'Documentation/networking/page_pool.rst')
| -rw-r--r-- | Documentation/networking/page_pool.rst | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/Documentation/networking/page_pool.rst b/Documentation/networking/page_pool.rst index a147591ce203..5db8c263b0c6 100644 --- a/Documentation/networking/page_pool.rst +++ b/Documentation/networking/page_pool.rst @@ -105,6 +105,47 @@ a page will cause no race conditions is enough. Please note the caller must not use data area after running page_pool_put_page_bulk(), as this function overwrites it. +* page_pool_get_stats(): Retrieve statistics about the page_pool. This API + is only available if the kernel has been configured with + ``CONFIG_PAGE_POOL_STATS=y``. A pointer to a caller allocated ``struct + page_pool_stats`` structure is passed to this API which is filled in. The + caller can then report those stats to the user (perhaps via ethtool, + debugfs, etc.). See below for an example usage of this API. + +Stats API and structures +------------------------ +If the kernel is configured with ``CONFIG_PAGE_POOL_STATS=y``, the API +``page_pool_get_stats()`` and structures described below are available. It +takes a pointer to a ``struct page_pool`` and a pointer to a ``struct +page_pool_stats`` allocated by the caller. + +The API will fill in the provided ``struct page_pool_stats`` with +statistics about the page_pool. + +The stats structure has the following fields:: + + struct page_pool_stats { + struct page_pool_alloc_stats alloc_stats; + struct page_pool_recycle_stats recycle_stats; + }; + + +The ``struct page_pool_alloc_stats`` has the following fields: + * ``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. + +The ``struct page_pool_recycle_stats`` has the following fields: + * ``cached``: recycling placed page in the page pool cache + * ``cache_full``: page pool cache was full + * ``ring``: page placed into the ptr ring + * ``ring_full``: page released from page pool because the ptr ring was full + * ``released_refcnt``: page released (and not recycled) because refcnt > 1 + Coding examples =============== @@ -157,6 +198,21 @@ NAPI poller } } +Stats +----- + +.. code-block:: c + + #ifdef CONFIG_PAGE_POOL_STATS + /* retrieve stats */ + struct page_pool_stats stats = { 0 }; + if (page_pool_get_stats(page_pool, &stats)) { + /* perhaps the driver reports statistics with ethool */ + ethtool_print_allocation_stats(&stats.alloc_stats); + ethtool_print_recycle_stats(&stats.recycle_stats); + } + #endif + Driver unload ------------- |