As more drivers begin to use the frag API, update the
document about how to decide which API to use for the
driver author.
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
CC: Lorenzo Bianconi <lorenzo@kernel.org>
CC: Alexander Duyck <alexander.duyck@gmail.com>
CC: Liang Chen <liangchen.linux@gmail.com>
CC: Alexander Lobakin <aleksander.lobakin@intel.com>
---
Documentation/networking/page_pool.rst | 4 +-
include/net/page_pool/helpers.h | 58 +++++++++++++++++++++++---
2 files changed, 55 insertions(+), 7 deletions(-)
diff --git a/Documentation/networking/page_pool.rst b/Documentation/networking/page_pool.rst
index 215ebc92752c..0c0705994f51 100644
--- a/Documentation/networking/page_pool.rst
+++ b/Documentation/networking/page_pool.rst
@@ -58,7 +58,9 @@ a page will cause no race conditions is enough.
.. kernel-doc:: include/net/page_pool/helpers.h
:identifiers: page_pool_put_page page_pool_put_full_page
- page_pool_recycle_direct page_pool_dev_alloc_pages
+ page_pool_recycle_direct page_pool_cache_free
+ page_pool_dev_alloc_pages page_pool_dev_alloc_frag
+ page_pool_dev_alloc page_pool_dev_cache_alloc
page_pool_get_dma_addr page_pool_get_dma_dir
.. kernel-doc:: net/core/page_pool.c
diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index b920224f6584..0f1eaa2986f9 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -8,13 +8,28 @@
/**
* DOC: page_pool allocator
*
- * The page_pool allocator is optimized for the XDP mode that
- * uses one frame per-page, but it can fallback on the
- * regular page allocator APIs.
+ * The page_pool allocator is optimized for recycling page or page frag used by
+ * skb packet and xdp frame.
*
- * Basic use involves replacing alloc_pages() calls with the
- * page_pool_alloc_pages() call. Drivers should use
- * page_pool_dev_alloc_pages() replacing dev_alloc_pages().
+ * Basic use involves replacing napi_alloc_frag() and alloc_pages() calls with
+ * page_pool_cache_alloc() and page_pool_alloc(), which allocate memory with or
+ * without page splitting depending on the requested memory size.
+ *
+ * If the driver knows that it always requires full pages or its allocates are
+ * always smaller than half a page, it can use one of the more specific API
+ * calls:
+ *
+ * 1. page_pool_alloc_pages(): allocate memory without page splitting when
+ * driver knows that the memory it need is always bigger than half of the page
+ * allocated from page pool. There is no cache line dirtying for 'struct page'
+ * when a page is recycled back to the page pool.
+ *
+ * 2. page_pool_alloc_frag(): allocate memory with page splitting when driver
+ * knows that the memory it need is always smaller than or equal to half of the
+ * page allocated from page pool. Page splitting enables memory saving and thus
+ * avoid TLB/cache miss for data access, but there also is some cost to
+ * implement page splitting, mainly some cache line dirtying/bouncing for
+ * 'struct page' and atomic operation for page->pp_frag_count.
*
* API keeps track of in-flight pages, in order to let API user know
* when it is safe to free a page_pool object. Thus, API users
@@ -100,6 +115,14 @@ static inline struct page *page_pool_alloc_frag(struct page_pool *pool,
return __page_pool_alloc_frag(pool, offset, size, gfp);
}
+/**
+ * page_pool_dev_alloc_frag() - allocate a page frag.
+ * @pool[in] pool from which to allocate
+ * @offset[out] offset to the allocated page
+ * @size[in] requested size
+ *
+ * Get a page frag from the page allocator or page_pool caches.
+ */
static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
unsigned int *offset,
unsigned int size)
@@ -143,6 +166,14 @@ static inline struct page *page_pool_alloc(struct page_pool *pool,
return page;
}
+/**
+ * page_pool_dev_alloc() - allocate a page or a page frag.
+ * @pool[in]: pool from which to allocate
+ * @offset[out]: offset to the allocated page
+ * @size[in, out]: in as the requested size, out as the allocated size
+ *
+ * Get a page or a page frag from the page allocator or page_pool caches.
+ */
static inline struct page *page_pool_dev_alloc(struct page_pool *pool,
unsigned int *offset,
unsigned int *size)
@@ -165,6 +196,13 @@ static inline void *page_pool_cache_alloc(struct page_pool *pool,
return page_address(page) + offset;
}
+/**
+ * page_pool_dev_cache_alloc() - allocate a cache.
+ * @pool[in]: pool from which to allocate
+ * @size[in, out]: in as the requested size, out as the allocated size
+ *
+ * Get a cache from the page allocator or page_pool caches.
+ */
static inline void *page_pool_dev_cache_alloc(struct page_pool *pool,
unsigned int *size)
{
@@ -316,6 +354,14 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
page_pool_put_full_page(pool, page, true);
}
+/**
+ * page_pool_cache_free() - free a cache into the page_pool
+ * @pool[in]: pool from which cache was allocated
+ * @data[in]: cache to free
+ * @allow_direct[in]: freed by the consumer, allow lockless caching
+ *
+ * Free a cache allocated from page_pool_dev_cache_alloc().
+ */
static inline void page_pool_cache_free(struct page_pool *pool, void *data,
bool allow_direct)
{
--
2.33.0Hi--
On 8/14/23 05:56, Yunsheng Lin wrote:
> As more drivers begin to use the frag API, update the
> document about how to decide which API to use for the
> driver author.
>
> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> CC: Lorenzo Bianconi <lorenzo@kernel.org>
> CC: Alexander Duyck <alexander.duyck@gmail.com>
> CC: Liang Chen <liangchen.linux@gmail.com>
> CC: Alexander Lobakin <aleksander.lobakin@intel.com>
> ---
> Documentation/networking/page_pool.rst | 4 +-
> include/net/page_pool/helpers.h | 58 +++++++++++++++++++++++---
> 2 files changed, 55 insertions(+), 7 deletions(-)
>
> diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
> index b920224f6584..0f1eaa2986f9 100644
> --- a/include/net/page_pool/helpers.h
> +++ b/include/net/page_pool/helpers.h
> @@ -8,13 +8,28 @@
> /**
> * DOC: page_pool allocator
> *
> - * The page_pool allocator is optimized for the XDP mode that
> - * uses one frame per-page, but it can fallback on the
> - * regular page allocator APIs.
> + * The page_pool allocator is optimized for recycling page or page frag used by
> + * skb packet and xdp frame.
> *
> - * Basic use involves replacing alloc_pages() calls with the
> - * page_pool_alloc_pages() call. Drivers should use
> - * page_pool_dev_alloc_pages() replacing dev_alloc_pages().
> + * Basic use involves replacing napi_alloc_frag() and alloc_pages() calls with
> + * page_pool_cache_alloc() and page_pool_alloc(), which allocate memory with or
> + * without page splitting depending on the requested memory size.
> + *
> + * If the driver knows that it always requires full pages or its allocates are
allocations
> + * always smaller than half a page, it can use one of the more specific API
> + * calls:
> + *
> + * 1. page_pool_alloc_pages(): allocate memory without page splitting when
> + * driver knows that the memory it need is always bigger than half of the page
> + * allocated from page pool. There is no cache line dirtying for 'struct page'
> + * when a page is recycled back to the page pool.
> + *
> + * 2. page_pool_alloc_frag(): allocate memory with page splitting when driver
> + * knows that the memory it need is always smaller than or equal to half of the
> + * page allocated from page pool. Page splitting enables memory saving and thus
> + * avoid TLB/cache miss for data access, but there also is some cost to
avoids
> + * implement page splitting, mainly some cache line dirtying/bouncing for
> + * 'struct page' and atomic operation for page->pp_frag_count.
> *
> * API keeps track of in-flight pages, in order to let API user know
> * when it is safe to free a page_pool object. Thus, API users
> @@ -100,6 +115,14 @@ static inline struct page *page_pool_alloc_frag(struct page_pool *pool,
> return __page_pool_alloc_frag(pool, offset, size, gfp);
> }
>
> +/**
> + * page_pool_dev_alloc_frag() - allocate a page frag.
> + * @pool[in] pool from which to allocate
> + * @offset[out] offset to the allocated page
> + * @size[in] requested size
Please use kernel-doc syntax/notation here.
> + *
> + * Get a page frag from the page allocator or page_pool caches.
> + */
> static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
> unsigned int *offset,
> unsigned int size)
> @@ -143,6 +166,14 @@ static inline struct page *page_pool_alloc(struct page_pool *pool,
> return page;
> }
>
> +/**
> + * page_pool_dev_alloc() - allocate a page or a page frag.
> + * @pool[in]: pool from which to allocate
> + * @offset[out]: offset to the allocated page
> + * @size[in, out]: in as the requested size, out as the allocated size
and here.
> + *
> + * Get a page or a page frag from the page allocator or page_pool caches.
> + */
> static inline struct page *page_pool_dev_alloc(struct page_pool *pool,
> unsigned int *offset,
> unsigned int *size)
> @@ -165,6 +196,13 @@ static inline void *page_pool_cache_alloc(struct page_pool *pool,
> return page_address(page) + offset;
> }
>
> +/**
> + * page_pool_dev_cache_alloc() - allocate a cache.
> + * @pool[in]: pool from which to allocate
> + * @size[in, out]: in as the requested size, out as the allocated size
and here.
> + *
> + * Get a cache from the page allocator or page_pool caches.
> + */
> static inline void *page_pool_dev_cache_alloc(struct page_pool *pool,
> unsigned int *size)
> {
> @@ -316,6 +354,14 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
> page_pool_put_full_page(pool, page, true);
> }
>
> +/**
> + * page_pool_cache_free() - free a cache into the page_pool
> + * @pool[in]: pool from which cache was allocated
> + * @data[in]: cache to free
> + * @allow_direct[in]: freed by the consumer, allow lockless caching
and here.
> + *
> + * Free a cache allocated from page_pool_dev_cache_alloc().
> + */
> static inline void page_pool_cache_free(struct page_pool *pool, void *data,
> bool allow_direct)
> {
Thanks.
On 2023/8/15 6:42, Randy Dunlap wrote:
> Hi--
Thanks for the reviewing.
>
...
>> @@ -100,6 +115,14 @@ static inline struct page *page_pool_alloc_frag(struct page_pool *pool,
>> return __page_pool_alloc_frag(pool, offset, size, gfp);
>> }
>> +/**
>> + * page_pool_dev_alloc_frag() - allocate a page frag.
>> + * @pool[in] pool from which to allocate
>> + * @offset[out] offset to the allocated page
>> + * @size[in] requested size
>
> Please use kernel-doc syntax/notation here.
Will change to:
/**
* page_pool_dev_alloc_frag() - allocate a page frag.
* @pool: pool from which to allocate
* @offset: offset to the allocated page
* @size: requested size
*
* Get a page frag from the page allocator or page_pool caches.
*
* Return:
* Returns allocated page frag, otherwise return NULL.
*/
>
>> + *
>> + * Get a page frag from the page allocator or page_pool caches.
>> + */
>> static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool,
>> unsigned int *offset,
>> unsigned int size)
>> @@ -143,6 +166,14 @@ static inline struct page *page_pool_alloc(struct page_pool *pool,
>> return page;
>> }
>> +/**
>> + * page_pool_dev_alloc() - allocate a page or a page frag.
>> + * @pool[in]: pool from which to allocate
>> + * @offset[out]: offset to the allocated page
>> + * @size[in, out]: in as the requested size, out as the allocated size
>
> and here.
/**
* page_pool_dev_alloc() - allocate a page or a page frag.
* @pool: pool from which to allocate
* @offset: offset to the allocated page
* @size: in as the requested size, out as the allocated size
*
* Get a page or a page frag from the page allocator or page_pool caches.
*
* Return:
* Returns a page or a page frag, otherwise return NULL.
*/
>
>> + *
>> + * Get a page or a page frag from the page allocator or page_pool caches.
>> + */
>> static inline struct page *page_pool_dev_alloc(struct page_pool *pool,
>> unsigned int *offset,
>> unsigned int *size)
>> @@ -165,6 +196,13 @@ static inline void *page_pool_cache_alloc(struct page_pool *pool,
>> return page_address(page) + offset;
>> }
>> +/**
>> + * page_pool_dev_cache_alloc() - allocate a cache.
>> + * @pool[in]: pool from which to allocate
>> + * @size[in, out]: in as the requested size, out as the allocated size
>
> and here.
/**
* page_pool_dev_cache_alloc() - allocate a cache.
* @pool: pool from which to allocate
* @size: in as the requested size, out as the allocated size
*
* Get a cache from the page allocator or page_pool caches.
*
* Return:
* Returns the addr for the allocated cache, otherwise return NULL.
*/
>
>> + *
>> + * Get a cache from the page allocator or page_pool caches.
>> + */
>> static inline void *page_pool_dev_cache_alloc(struct page_pool *pool,
>> unsigned int *size)
>> {
>> @@ -316,6 +354,14 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
>> page_pool_put_full_page(pool, page, true);
>> }
>> +/**
>> + * page_pool_cache_free() - free a cache into the page_pool
>> + * @pool[in]: pool from which cache was allocated
>> + * @data[in]: cache to free
>> + * @allow_direct[in]: freed by the consumer, allow lockless caching
>
> and here.
/**
* page_pool_cache_free() - free a cache into the page_pool
* @pool: pool from which cache was allocated
* @data: addr of cache to be free
* @allow_direct: freed by the consumer, allow lockless caching
*
* Free a cache allocated from page_pool_dev_cache_alloc().
*/
>
>> + *
>> + * Free a cache allocated from page_pool_dev_cache_alloc().
>> + */
>> static inline void page_pool_cache_free(struct page_pool *pool, void *data,
>> bool allow_direct)
>> {
>
> Thanks.
On 8/15/23 05:24, Yunsheng Lin wrote: > On 2023/8/15 6:42, Randy Dunlap wrote: >> Hi-- > Thanks for the reviewing. > > ... > >>> @@ -100,6 +115,14 @@ static inline struct page *page_pool_alloc_frag(struct page_pool *pool, >>> return __page_pool_alloc_frag(pool, offset, size, gfp); >>> } >>> +/** >>> + * page_pool_dev_alloc_frag() - allocate a page frag. >>> + * @pool[in] pool from which to allocate >>> + * @offset[out] offset to the allocated page >>> + * @size[in] requested size >> Please use kernel-doc syntax/notation here. > Will change to: Thanks. Those look good. -- ~Randy
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