Messages in this thread Patch in this message | | | From | Yunsheng Lin <> | Subject | [PATCH net-next 2/2] page_pool: support non-frag page for page_pool_alloc_frag() | Date | Fri, 26 May 2023 17:26:15 +0800 |
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There is performance penalty with using page frag support when user requests a larger frag size and a page only supports one frag user, see [1].
It seems like user may request different frag size depending on the mtu and packet size, provide an option to allocate non-frag page when a whole page is not able to hold two frags, so that user has a unified interface for the memory allocation with least memory utilization and performance penalty.
1. https://lore.kernel.org/netdev/ZEU+vospFdm08IeE@localhost.localdomain/
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> CC: Lorenzo Bianconi <lorenzo@kernel.org> CC: Alexander Duyck <alexander.duyck@gmail.com> --- net/core/page_pool.c | 47 +++++++++++++++++++++++++++----------------- 1 file changed, 29 insertions(+), 18 deletions(-)
diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 0868aa8f6323..e84ec6eabefd 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -699,14 +699,27 @@ struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int max_size = PAGE_SIZE << pool->p.order; struct page *page = pool->frag_page; - if (WARN_ON(!(pool->p.flags & PP_FLAG_PAGE_FRAG) || - size > max_size)) + if (unlikely(size > max_size)) return NULL; + if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) { + *offset = 0; + return page_pool_alloc_pages(pool, gfp); + } + size = ALIGN(size, dma_get_cache_alignment()); - *offset = pool->frag_offset; - if (page && *offset + size > max_size) { + if (page) { + *offset = pool->frag_offset; + + if (*offset + size <= max_size) { + pool->frag_users++; + pool->frag_offset = *offset + size; + alloc_stat_inc(pool, fast); + return page; + } + + pool->frag_page = NULL; page = page_pool_drain_frag(pool, page); if (page) { alloc_stat_inc(pool, fast); @@ -714,26 +727,24 @@ struct page *page_pool_alloc_frag(struct page_pool *pool, } } - if (!page) { - page = page_pool_alloc_pages(pool, gfp); - if (unlikely(!page)) { - pool->frag_page = NULL; - return NULL; - } - - pool->frag_page = page; + page = page_pool_alloc_pages(pool, gfp); + if (unlikely(!page)) + return NULL; frag_reset: - pool->frag_users = 1; + /* return page as non-frag page if a page is not able to + * hold two frags for the current requested size. + */ + if (unlikely(size << 1 > max_size)) { *offset = 0; - pool->frag_offset = size; - page_pool_fragment_page(page, BIAS_MAX); return page; } - pool->frag_users++; - pool->frag_offset = *offset + size; - alloc_stat_inc(pool, fast); + pool->frag_page = page; + pool->frag_users = 1; + *offset = 0; + pool->frag_offset = size; + page_pool_fragment_page(page, BIAS_MAX); return page; } EXPORT_SYMBOL(page_pool_alloc_frag); -- 2.33.0
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