From patchwork Wed Dec 6 10:54:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13481490 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Y4/ZG+YU" Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52E809C for ; Wed, 6 Dec 2023 02:54:38 -0800 (PST) Received: by mail-pf1-x42f.google.com with SMTP id d2e1a72fcca58-6cbd24d9557so590256b3a.1 for ; Wed, 06 Dec 2023 02:54:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701860078; x=1702464878; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=VMA+wq9Jm0b7Bol6yd6xB1YlXbaZgXyOcITML8JglNg=; b=Y4/ZG+YUtEypVnH2cD591jdB49l0mymPyv0hs9mVaX+eAvsNvIkaWKNSSIBRK4GRfP iocsGIO0+6t9AYJKHkLcDgoaYwB5RN0vzOHi8NKSEVGc+hB8TACQWPCj7PYS+iq6HkeY uED6+z0VZL7fN/pg+e1nc9UCfJ7DJYiMNzxi647kGq8phcpZ/72QvbZtxZGya9hnjou/ p5MwKK5+4mnW4xKNPDnMHnOz84vWLcLvllgBucvm39xrHWqEL5st8hRYARKhx7/mZX36 bK5C4Y5wFUJoU5HzibXDglT8Nxe6pIw1Ubjm3C+3/5A06sBhfzjXr9kiP31gGZeZ8XVj Ypkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701860078; x=1702464878; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=VMA+wq9Jm0b7Bol6yd6xB1YlXbaZgXyOcITML8JglNg=; b=Gm1mvlNDashxEY537xyKNNqg7HMIwEnTqeOZVj8Q2xdoHmitWSTi/+d5WWOZZ7p9QF xFE5PQpnFiq8Qb/+Kx4WatQhaoGtO+CzjziChMO5IqX0vC0cgIHcdYSzd/SEPV1Kjj1A en+AlvtXviiHUfMeY9c0ulKEHOXYqowo+wbz/xcTk6d9jcHGbAN7XmOu6JIY+NGl3rhG RKBSOKLnQejPIOeCoJxOmSvjSKgUO9riOERl1Ftkb/NSRQBTIyAhywgj5bdMQnnpw/7l 4xNxzhxq5z12ZWKTiGUE21sMMV+CbQeawnMtnaHDsOdhu2XPe2Ns6ZxLsUpXpPJ+4/+r ur+g== X-Gm-Message-State: AOJu0YxZs3FgzEULUAEZ8js0vVC5+XgYOOh920iAkKBiiPM1k7kdm2hl vm539bu7+CMecxXgWtWDbvA= X-Google-Smtp-Source: AGHT+IHlsRemaAZ0vBp17tCrbsNHx/YNozwjCObQMRxRWtB6pKqVA9DflSCz1o43HJA/xLHxeOQQUg== X-Received: by 2002:a05:6a00:b4d:b0:6ce:78c9:5979 with SMTP id p13-20020a056a000b4d00b006ce78c95979mr2108126pfo.18.1701860077567; Wed, 06 Dec 2023 02:54:37 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id n15-20020a638f0f000000b005c6801efa0fsm5388796pgd.28.2023.12.06.02.54.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 02:54:36 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, jasowang@redhat.com, liangchen.linux@gmail.com Subject: [PATCH net-next v7 1/4] page_pool: transition to reference count management after page draining Date: Wed, 6 Dec 2023 18:54:16 +0800 Message-Id: <20231206105419.27952-2-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231206105419.27952-1-liangchen.linux@gmail.com> References: <20231206105419.27952-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org To support multiple users referencing the same fragment, 'pp_frag_count' is renamed to 'pp_ref_count', transitioning pp pages from fragment management to reference count management after draining based on the suggestion from [1]. The idea is that the concept of fragmenting exists before the page is drained, and all related functions retain their current names. However, once the page is drained, its management shifts to being governed by 'pp_ref_count'. Therefore, all functions associated with that lifecycle stage of a pp page are renamed. [1] http://lore.kernel.org/netdev/f71d9448-70c8-8793-dc9a-0eb48a570300@huawei.com Signed-off-by: Liang Chen Reviewed-by: Yunsheng Lin --- .../net/ethernet/mellanox/mlx5/core/en_rx.c | 4 +- include/linux/mm_types.h | 2 +- include/net/page_pool/helpers.h | 45 ++++++++++--------- include/net/page_pool/types.h | 6 +-- net/core/page_pool.c | 12 ++--- 5 files changed, 37 insertions(+), 32 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c index 8d9743a5e42c..98d33ac7ec64 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c @@ -298,8 +298,8 @@ static void mlx5e_page_release_fragmented(struct mlx5e_rq *rq, u16 drain_count = MLX5E_PAGECNT_BIAS_MAX - frag_page->frags; struct page *page = frag_page->page; - if (page_pool_defrag_page(page, drain_count) == 0) - page_pool_put_defragged_page(rq->page_pool, page, -1, true); + if (page_pool_unref_page(page, drain_count) == 0) + page_pool_put_unrefed_page(rq->page_pool, page, -1, true); } static inline int mlx5e_get_rx_frag(struct mlx5e_rq *rq, diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 957ce38768b2..64e4572ef06d 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -125,7 +125,7 @@ struct page { struct page_pool *pp; unsigned long _pp_mapping_pad; unsigned long dma_addr; - atomic_long_t pp_frag_count; + atomic_long_t pp_ref_count; }; struct { /* Tail pages of compound page */ unsigned long compound_head; /* Bit zero is set */ diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 4ebd544ae977..9dc8eaf8a959 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -29,7 +29,7 @@ * page allocated from page pool. Page splitting enables memory saving and thus * avoids 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. + * 'struct page' and atomic operation for page->pp_ref_count. * * The API keeps track of in-flight pages, in order to let API users know when * it is safe to free a page_pool object, the API users must call @@ -214,69 +214,74 @@ inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool) return pool->p.dma_dir; } -/* pp_frag_count represents the number of writers who can update the page +/* pp_ref_count represents the number of writers who can update the page * either by updating skb->data or via DMA mappings for the device. * We can't rely on the page refcnt for that as we don't know who might be * holding page references and we can't reliably destroy or sync DMA mappings * of the fragments. * - * When pp_frag_count reaches 0 we can either recycle the page if the page + * pp_ref_count initially corresponds to the number of fragments. However, + * when multiple users start to reference a single fragment, for example in + * skb_try_coalesce, the pp_ref_count will become greater than the number of + * fragments. + * + * When pp_ref_count reaches 0 we can either recycle the page if the page * refcnt is 1 or return it back to the memory allocator and destroy any * mappings we have. */ static inline void page_pool_fragment_page(struct page *page, long nr) { - atomic_long_set(&page->pp_frag_count, nr); + atomic_long_set(&page->pp_ref_count, nr); } -static inline long page_pool_defrag_page(struct page *page, long nr) +static inline long page_pool_unref_page(struct page *page, long nr) { long ret; - /* If nr == pp_frag_count then we have cleared all remaining + /* If nr == pp_ref_count then we have cleared all remaining * references to the page: * 1. 'n == 1': no need to actually overwrite it. * 2. 'n != 1': overwrite it with one, which is the rare case - * for pp_frag_count draining. + * for pp_ref_count draining. * * The main advantage to doing this is that not only we avoid a atomic * update, as an atomic_read is generally a much cheaper operation than * an atomic update, especially when dealing with a page that may be - * partitioned into only 2 or 3 pieces; but also unify the pp_frag_count + * referenced by only 2 or 3 users; but also unify the pp_ref_count * handling by ensuring all pages have partitioned into only 1 piece * initially, and only overwrite it when the page is partitioned into * more than one piece. */ - if (atomic_long_read(&page->pp_frag_count) == nr) { + if (atomic_long_read(&page->pp_ref_count) == nr) { /* As we have ensured nr is always one for constant case using * the BUILD_BUG_ON(), only need to handle the non-constant case - * here for pp_frag_count draining, which is a rare case. + * here for pp_ref_count draining, which is a rare case. */ BUILD_BUG_ON(__builtin_constant_p(nr) && nr != 1); if (!__builtin_constant_p(nr)) - atomic_long_set(&page->pp_frag_count, 1); + atomic_long_set(&page->pp_ref_count, 1); return 0; } - ret = atomic_long_sub_return(nr, &page->pp_frag_count); + ret = atomic_long_sub_return(nr, &page->pp_ref_count); WARN_ON(ret < 0); - /* We are the last user here too, reset pp_frag_count back to 1 to + /* We are the last user here too, reset pp_ref_count back to 1 to * ensure all pages have been partitioned into 1 piece initially, * this should be the rare case when the last two fragment users call - * page_pool_defrag_page() currently. + * page_pool_unref_page() currently. */ if (unlikely(!ret)) - atomic_long_set(&page->pp_frag_count, 1); + atomic_long_set(&page->pp_ref_count, 1); return ret; } -static inline bool page_pool_is_last_frag(struct page *page) +static inline bool page_pool_is_last_ref(struct page *page) { - /* If page_pool_defrag_page() returns 0, we were the last user */ - return page_pool_defrag_page(page, 1) == 0; + /* If page_pool_unref_page() returns 0, we were the last user */ + return page_pool_unref_page(page, 1) == 0; } /** @@ -301,10 +306,10 @@ static inline void page_pool_put_page(struct page_pool *pool, * allow registering MEM_TYPE_PAGE_POOL, but shield linker. */ #ifdef CONFIG_PAGE_POOL - if (!page_pool_is_last_frag(page)) + if (!page_pool_is_last_ref(page)) return; - page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct); + page_pool_put_unrefed_page(pool, page, dma_sync_size, allow_direct); #endif } diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h index e1bb92c192de..6a5323619f6e 100644 --- a/include/net/page_pool/types.h +++ b/include/net/page_pool/types.h @@ -224,9 +224,9 @@ static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data, } #endif -void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, - unsigned int dma_sync_size, - bool allow_direct); +void page_pool_put_unrefed_page(struct page_pool *pool, struct page *page, + unsigned int dma_sync_size, + bool allow_direct); static inline bool is_page_pool_compiled_in(void) { diff --git a/net/core/page_pool.c b/net/core/page_pool.c index df2a06d7da52..106220b1f89c 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -650,8 +650,8 @@ __page_pool_put_page(struct page_pool *pool, struct page *page, return NULL; } -void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, - unsigned int dma_sync_size, bool allow_direct) +void page_pool_put_unrefed_page(struct page_pool *pool, struct page *page, + unsigned int dma_sync_size, bool allow_direct) { page = __page_pool_put_page(pool, page, dma_sync_size, allow_direct); if (page && !page_pool_recycle_in_ring(pool, page)) { @@ -660,7 +660,7 @@ void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, page_pool_return_page(pool, page); } } -EXPORT_SYMBOL(page_pool_put_defragged_page); +EXPORT_SYMBOL(page_pool_put_unrefed_page); /** * page_pool_put_page_bulk() - release references on multiple pages @@ -687,7 +687,7 @@ void page_pool_put_page_bulk(struct page_pool *pool, void **data, struct page *page = virt_to_head_page(data[i]); /* It is not the last user for the page frag case */ - if (!page_pool_is_last_frag(page)) + if (!page_pool_is_last_ref(page)) continue; page = __page_pool_put_page(pool, page, -1, false); @@ -729,7 +729,7 @@ static struct page *page_pool_drain_frag(struct page_pool *pool, long drain_count = BIAS_MAX - pool->frag_users; /* Some user is still using the page frag */ - if (likely(page_pool_defrag_page(page, drain_count))) + if (likely(page_pool_unref_page(page, drain_count))) return NULL; if (page_ref_count(page) == 1 && !page_is_pfmemalloc(page)) { @@ -750,7 +750,7 @@ static void page_pool_free_frag(struct page_pool *pool) pool->frag_page = NULL; - if (!page || page_pool_defrag_page(page, drain_count)) + if (!page || page_pool_unref_page(page, drain_count)) return; page_pool_return_page(pool, page); From patchwork Wed Dec 6 10:54:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13481491 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QHxsw7HF" Received: from mail-ot1-x32f.google.com (mail-ot1-x32f.google.com [IPv6:2607:f8b0:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 704BE9C for ; 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bh=J730iItaW8fpD9bcYiCc3WSDtwgBtsyA2Jb0R83edv4=; b=YXRreV/A1SUmCV41oNjNWlczcJ0fjVMDLyph8A3jPKCLskElgOQSn0VyFCFwavLKpL iqGGx0mD73ziShlx7e9Yykr8WykBepiS31eiKUs8zsQOBy5GwNArtaDSyTWi3g0RzRb3 cU3cUmPJ1xpnmMolVk5jErtRkqfT1qkpK2H2ZYh5W8ZGtyJrHaonJnzsrTgAt/v0GI/y kyTIEmQKh8tAlNZiOPgbl00orOvwRoRVKn0oiOo58my/g5SQnU3nEQHaVW356WRC15gj hJX2cuVjKWN6VrxDCo0+HHhP1A6wh4uCY7PzpE4m2NzmHyyMLeVvVTIH0RNPvAwZ5bGz CDIw== X-Gm-Message-State: AOJu0YwAaxoUDBgWaiixDlo6JBZg8LrsjUH+fD91ulPTJaGaBV4gl08p tB1jx7MxjzgeTUdMQI5l+P4= X-Google-Smtp-Source: AGHT+IEVWGAs6VmJ6gEEtOq16rEzedYFdHy4Uqdvgzphsz0NsAg1Zhi+SY0iNk9q2PpSNior2r90BQ== X-Received: by 2002:a05:6830:1117:b0:6d6:4ebf:1557 with SMTP id w23-20020a056830111700b006d64ebf1557mr580766otq.21.1701860082740; Wed, 06 Dec 2023 02:54:42 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id n15-20020a638f0f000000b005c6801efa0fsm5388796pgd.28.2023.12.06.02.54.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 02:54:41 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, jasowang@redhat.com, liangchen.linux@gmail.com Subject: [PATCH net-next v7 2/4] page_pool: halve BIAS_MAX for multiple user references of a fragment Date: Wed, 6 Dec 2023 18:54:17 +0800 Message-Id: <20231206105419.27952-3-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231206105419.27952-1-liangchen.linux@gmail.com> References: <20231206105419.27952-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Referring to patch [1], in order to support multiple users referencing the same fragment and prevent overflow from pp_ref_count growing, the initial value of pp_ref_count is halved, leaving room for pp_ref_count to increment before the page is drained. [1] https://lore.kernel.org/all/20211009093724.10539-3-linyunsheng@huawei.com/ Signed-off-by: Liang Chen Reviewed-by: Yunsheng Lin --- net/core/page_pool.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 106220b1f89c..436f7ffea7b4 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -26,7 +26,7 @@ #define DEFER_TIME (msecs_to_jiffies(1000)) #define DEFER_WARN_INTERVAL (60 * HZ) -#define BIAS_MAX LONG_MAX +#define BIAS_MAX (LONG_MAX >> 1) #ifdef CONFIG_PAGE_POOL_STATS /* alloc_stat_inc is intended to be used in softirq context */ From patchwork Wed Dec 6 10:54:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13481492 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Lg7pYInd" Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6DD7A9 for ; Wed, 6 Dec 2023 02:54:48 -0800 (PST) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-6cb55001124so572033b3a.0 for ; Wed, 06 Dec 2023 02:54:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701860088; x=1702464888; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=G2d8n0WXue9ygrbxloUCx8WAoE9HhkQ6PXxWrjAEYxU=; b=Lg7pYIndf61QlWmisT1xcj50caZkOYEXWP/lIJCmvqSCc0xP6GjZ6KgBZjb+Ogv4f1 8cT0H8Cixtmg2O3JC3p04iopvY5ePpfDBVa0OF1tR1AHD1HncnvOGIiHUUb2q1FMLslB losWj1b+gL4VhILdX1bL2sgO8S6ig16OpNQOa032il+W91m6z9aD9uZc/Dxyp1mnMNvw VbLzYeR+aRFDUNo3vlqszGWeuJn6ZwTYNpl/PYsM3QNykZgFwC1eleWVavYflfxgGM3/ raO9+H4XLkMTYfEuavRgxYHtC4gR30nbt31TCbVyHYE+9NR4N8dVpo3Al+BQG/Nc0IIl MEgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701860088; x=1702464888; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=G2d8n0WXue9ygrbxloUCx8WAoE9HhkQ6PXxWrjAEYxU=; b=l08+POpgEmKNnd2lDB1TgfL2XElDbGtOtrSayOLqyAKi87kka05IVIpkrYVEr356ZO Iw+1kR81yRPQNxfRnO2iehbcjb0sT4AdiJPb6f2UQtBVmnQb6MPzhJsbFAdck3NAaXlT Yd9XQUmO/G/wDf7CAf5qfL5YhbRyeyuhW6OjY1Kr76NyxCU4PijdNpgTIZjCNv8737rt 3gcKzuLK2KxyfBAfKs4mOR6AAgcy907FcEL+zWXuAWlomkBNyu0S5nBvAhPejhtak3Be EeqoJZEh2Gf9wMGMZdZoyZxNAzkc7oxlQk1w76Ioq30mExgisIUP5txNv6/hx3Gi0QTv n7Hw== X-Gm-Message-State: AOJu0YyN04dvFK2JG+I4BVnJ/rjoow66ogm/jizI2vUFGIUtDw2FecXC L92N4m58o18FnxS5b84CORE= X-Google-Smtp-Source: AGHT+IEd77h94hhs6J/CMTnJCe+7Ml/LiOxXG4jzQ3aQZou8zSYUeYniVYIbULJrzgmovOv3R+QYrA== X-Received: by 2002:a05:6a20:54a0:b0:18b:1a31:ee6a with SMTP id i32-20020a056a2054a000b0018b1a31ee6amr4104734pzk.23.1701860087999; Wed, 06 Dec 2023 02:54:47 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id n15-20020a638f0f000000b005c6801efa0fsm5388796pgd.28.2023.12.06.02.54.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 02:54:47 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, jasowang@redhat.com, liangchen.linux@gmail.com Subject: [PATCH net-next v7 3/4] skbuff: Add a function to check if a page belongs to page_pool Date: Wed, 6 Dec 2023 18:54:18 +0800 Message-Id: <20231206105419.27952-4-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231206105419.27952-1-liangchen.linux@gmail.com> References: <20231206105419.27952-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Wrap code for checking if a page is a page_pool page into a function for better readability and ease of reuse. Signed-off-by: Liang Chen Reviewed-by: Yunsheng Lin --- net/core/skbuff.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index b157efea5dea..7e26b56cda38 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -890,6 +890,11 @@ static void skb_clone_fraglist(struct sk_buff *skb) skb_get(list); } +static bool is_pp_page(struct page *page) +{ + return (page->pp_magic & ~0x3UL) == PP_SIGNATURE; +} + #if IS_ENABLED(CONFIG_PAGE_POOL) bool napi_pp_put_page(struct page *page, bool napi_safe) { @@ -905,7 +910,7 @@ bool napi_pp_put_page(struct page *page, bool napi_safe) * and page_is_pfmemalloc() is checked in __page_pool_put_page() * to avoid recycling the pfmemalloc page. */ - if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE)) + if (unlikely(!is_pp_page(page))) return false; pp = page->pp; From patchwork Wed Dec 6 10:54:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13481493 X-Patchwork-Delegate: kuba@kernel.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GKkY5RBh" Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E832A4 for ; Wed, 6 Dec 2023 02:54:54 -0800 (PST) Received: by mail-pf1-x433.google.com with SMTP id d2e1a72fcca58-6ce5a0c384fso2424712b3a.1 for ; Wed, 06 Dec 2023 02:54:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1701860094; x=1702464894; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=XJpeq0esGgvSQwPlWYu5mSKUKlrzr2fXLQ04GZyOjBI=; b=GKkY5RBhEugujfXGZA5eTzCLUzWXMrrW5rZmhxPn1VVY6GeTdTO5VDNSPXsXZlNhVd wyn05E8FZw4gNw/+vnMgJnW3Cd9Ev/s15wdksMmIuwEqUZ1EaWuVtY0RD+JxYo4oJPXQ UqQNKAdUR2I+w97tCoqm0QefRWdErIlAhYpeWC69Equ/aU2mfcjcv0r5YO9Jo7EQui1d sd9Y5rmHTxlhgOn5hJupRqz3ty60nYXi7xVoOMW6mtWKr6NCxqrs5bj/NoSNyueGFygz 5pbOY9oW1RlnJx9FIiEDv+CXy/hhum8jPUs9nihXqHAkKngigM25xyNvQzhAa9X6IBMv 0DXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701860094; x=1702464894; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=XJpeq0esGgvSQwPlWYu5mSKUKlrzr2fXLQ04GZyOjBI=; b=jFppUv1AUqeBLz82NRoIeJMDNCmrLJr7jXmPieJJZxrCqH2ovhCo+cXEUx+XS5gpCm +FbrJP0OX6cHfOlMtg+ThoWQWuSzjNR3wvNM5nkFrdysj68Usk+NaupUJzJEhI5Aks5O JRheYHevgGZt6MIZB5XHur/zNepbehB+PTRZPUe1Fy9S1E8fjjdQ3xs8hx7prYRQG2T8 RJb2mLV5F/ljI5T/QD7bZ+XA1H9ZJvGUNkV8QhJfekB7nYUQ3O8wKAoieh7UmGHgd74S aAYDiO2SopIGYikvjUPFMYaNxJm1T1V6FTzCiKTRR/YYBmsth6x0kWOyVnPCX8Wq4Z3j n8GA== X-Gm-Message-State: AOJu0YygSm1/9bCNGJZCQDLypSglVEcaApamX+SkUpjxW/qdHIxS7eNN VZhNEXXPAb845HDEKb7MWsw= X-Google-Smtp-Source: AGHT+IGs32UGGkDmx++vF2WrxMsf6vIKFr/2F29zLgzga5cW6Le3dLh6j/00l5geSI7if5bXr/dyag== X-Received: by 2002:a05:6a00:1743:b0:6ce:6c6d:1622 with SMTP id j3-20020a056a00174300b006ce6c6d1622mr514790pfc.62.1701860093745; Wed, 06 Dec 2023 02:54:53 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id n15-20020a638f0f000000b005c6801efa0fsm5388796pgd.28.2023.12.06.02.54.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Dec 2023 02:54:52 -0800 (PST) From: Liang Chen To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, hawk@kernel.org, ilias.apalodimas@linaro.org, linyunsheng@huawei.com Cc: netdev@vger.kernel.org, linux-mm@kvack.org, jasowang@redhat.com, liangchen.linux@gmail.com Subject: [PATCH net-next v7 4/4] skbuff: Optimization of SKB coalescing for page pool Date: Wed, 6 Dec 2023 18:54:19 +0800 Message-Id: <20231206105419.27952-5-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231206105419.27952-1-liangchen.linux@gmail.com> References: <20231206105419.27952-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org In order to address the issues encountered with commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment recycling"), the combination of the following condition was excluded from skb coalescing: from->pp_recycle = 1 from->cloned = 1 to->pp_recycle = 1 However, with page pool environments, the aforementioned combination can be quite common(ex. NetworkMananger may lead to the additional packet_type being registered, thus the cloning). In scenarios with a higher number of small packets, it can significantly affect the success rate of coalescing. For example, considering packets of 256 bytes size, our comparison of coalescing success rate is as follows: Without page pool: 70% With page pool: 13% Consequently, this has an impact on performance: Without page pool: 2.57 Gbits/sec With page pool: 2.26 Gbits/sec Therefore, it seems worthwhile to optimize this scenario and enable coalescing of this particular combination. To achieve this, we need to ensure the correct increment of the "from" SKB page's page pool reference count (pp_ref_count). Following this optimization, the success rate of coalescing measured in our environment has improved as follows: With page pool: 60% This success rate is approaching the rate achieved without using page pool, and the performance has also been improved: With page pool: 2.52 Gbits/sec Below is the performance comparison for small packets before and after this optimization. We observe no impact to packets larger than 4K. packet size before after improved (bytes) (Gbits/sec) (Gbits/sec) 128 1.19 1.27 7.13% 256 2.26 2.52 11.75% 512 4.13 4.81 16.50% 1024 6.17 6.73 9.05% 2048 14.54 15.47 6.45% 4096 25.44 27.87 9.52% Signed-off-by: Liang Chen Reviewed-by: Yunsheng Lin Suggested-by: Jason Wang --- include/net/page_pool/helpers.h | 5 ++++ net/core/skbuff.c | 41 +++++++++++++++++++++++---------- 2 files changed, 34 insertions(+), 12 deletions(-) diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h index 9dc8eaf8a959..268bc9d9ffd3 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -278,6 +278,11 @@ static inline long page_pool_unref_page(struct page *page, long nr) return ret; } +static inline void page_pool_ref_page(struct page *page) +{ + atomic_long_inc(&page->pp_ref_count); +} + static inline bool page_pool_is_last_ref(struct page *page) { /* If page_pool_unref_page() returns 0, we were the last user */ diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 7e26b56cda38..3c2515a29376 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -947,6 +947,24 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe) return napi_pp_put_page(virt_to_page(data), napi_safe); } +/** + * skb_pp_frag_ref() - Increase fragment reference count of a page + * @page: page of the fragment on which to increase a reference + * + * Increase fragment reference count (pp_ref_count) on a page, but if it is + * not a page pool page, fallback to increase a reference(_refcount) on a + * normal page. + */ +static void skb_pp_frag_ref(struct page *page) +{ + struct page *head_page = compound_head(page); + + if (likely(is_pp_page(head_page))) + page_pool_ref_page(head_page); + else + page_ref_inc(head_page); +} + static void skb_kfree_head(void *head, unsigned int end_offset) { if (end_offset == SKB_SMALL_HEAD_HEADROOM) @@ -5769,17 +5787,12 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, return false; /* In general, avoid mixing page_pool and non-page_pool allocated - * pages within the same SKB. Additionally avoid dealing with clones - * with page_pool pages, in case the SKB is using page_pool fragment - * references (page_pool_alloc_frag()). Since we only take full page - * references for cloned SKBs at the moment that would result in - * inconsistent reference counts. - * In theory we could take full references if @from is cloned and - * !@to->pp_recycle but its tricky (due to potential race with - * the clone disappearing) and rare, so not worth dealing with. + * pages within the same SKB. In theory we could take full + * references if @from is cloned and !@to->pp_recycle but its + * tricky (due to potential race with the clone disappearing) and + * rare, so not worth dealing with. */ - if (to->pp_recycle != from->pp_recycle || - (from->pp_recycle && skb_cloned(from))) + if (to->pp_recycle != from->pp_recycle) return false; if (len <= skb_tailroom(to)) { @@ -5836,8 +5849,12 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, /* if the skb is not cloned this does nothing * since we set nr_frags to 0. */ - for (i = 0; i < from_shinfo->nr_frags; i++) - __skb_frag_ref(&from_shinfo->frags[i]); + if (from->pp_recycle) + for (i = 0; i < from_shinfo->nr_frags; i++) + skb_pp_frag_ref(skb_frag_page(&from_shinfo->frags[i])); + else + for (i = 0; i < from_shinfo->nr_frags; i++) + __skb_frag_ref(&from_shinfo->frags[i]); to->truesize += delta; to->len += len;