From patchwork Mon Dec 11 03:52:40 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13486646 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="A+I6TxWw" Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E4DBF1 for ; Sun, 10 Dec 2023 19:53:15 -0800 (PST) Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1d0538d9bbcso37388095ad.3 for ; Sun, 10 Dec 2023 19:53:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702266794; x=1702871594; 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=0gkCO+cmYizzxtKpmJJFZh1hseverSK4jjEXH+6EVns=; b=A+I6TxWwu58j9O5g2vquGU+KWsQfqQIlWlIlmqdgl8WUXr79Ea8LFiVFtSoUpg6W2E Jjr5cyIGuCSBWSkz3SBCxhxPGLzP2iKsQqXld33IsBnVtdBbO9CaKq9s6bmjqdctV9uN G6+p0fDuzA3U7rtLvYRKFNqlhFYfbrPTRpmL2U2TRKmVAoyC9/5zvamwz1fxKg4OlkKJ 2j42iK76qMg1cgwgyjFWbSiHsfZAXL1s2n5U6TGl8lg6mwK+ZVIV/KY0IisHQ7fguD5k m1rHylH8MpK4LJNTDMAFc7Y4DBdtLJEZO4+X8djivsvwe0CYx81rj9rOiRt6PzaM/+77 XG6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702266794; x=1702871594; 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=0gkCO+cmYizzxtKpmJJFZh1hseverSK4jjEXH+6EVns=; b=r7+9tajVh9fjWaDx/k1QdiU5p43v2+pqYVUeSZydP/R2vIadPD6YM3H6h/zj3McdCh PPldlOOoRUhWQdgIwnNMVF/vPxFBm1Dc6+fOw+9PjrZQyS5X1gubEpr0dvzvJRwqGPnx 2cDlzpQX+SP4TfD4Kfxho4g2s+pdaNQCyVvVCjhAf5X8ngXiWUWdQEf2MqWTFMiT8vaJ xALhwOi1Xn3/RCmuVIVVC02UlyQIL28y9DeXw4GM6iB9SSxJCiHcDxY9CUMOl76ImzqC 13XddHzYOnVaeEEuRJO0D+PRlmqfTrjig22ONt8iVucspM42g4Penf0hPyc2Vka2dkcc TWYg== X-Gm-Message-State: AOJu0YytN9X1P5oXh76r6lyADAVjm0hPZdcXbxGvWnwC69BkkDjeq+rE VOcEbehbYkoFCRyOSjdcZYg= X-Google-Smtp-Source: AGHT+IEXf6IbJoR8Iz9MNTsR6P223Ynd+dcUtTQl8p+o+6SoIZRPusRJS8EGhxpR+3WfEFg3O3977A== X-Received: by 2002:a17:902:a5c7:b0:1d0:7844:5086 with SMTP id t7-20020a170902a5c700b001d078445086mr3242096plq.7.1702266794499; Sun, 10 Dec 2023 19:53:14 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id b8-20020a170903228800b001d052d1aaf2sm5411491plh.101.2023.12.10.19.53.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 19:53:13 -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, almasrymina@google.com, liangchen.linux@gmail.com Subject: [PATCH net-next v8 1/4] page_pool: transition to reference count management after page draining Date: Mon, 11 Dec 2023 11:52:40 +0800 Message-Id: <20231211035243.15774-2-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231211035243.15774-1-liangchen.linux@gmail.com> References: <20231211035243.15774-1-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 Reviewed-by: Ilias Apalodimas --- .../net/ethernet/mellanox/mlx5/core/en_rx.c | 4 +- include/linux/mm_types.h | 2 +- include/net/page_pool/helpers.h | 60 +++++++++++-------- include/net/page_pool/types.h | 6 +- net/core/page_pool.c | 12 ++-- 5 files changed, 46 insertions(+), 38 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..d0c5e7e6857a 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 +214,77 @@ 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 - * 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. +/** + * page_pool_fragment_page() - split a fresh page into fragments + * @page: page to split + * @nr: references to set + * + * pp_ref_count represents the number of outstanding references to the page, + * which will be freed using page_pool APIs (rather than page allocator APIs + * like put_page()). Such references are usually held by page_pool-aware + * objects like skbs marked for page pool recycling. * - * When pp_frag_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. + * This helper allows the caller to take (set) multiple references to a + * freshly allocated page. The page must be freshly allocated (have a + * pp_ref_count of 1). This is commonly done by drivers and + * "fragment allocators" to save atomic operations - either when they know + * upfront how many references they will need; or to take MAX references and + * return the unused ones with a single atomic dec(), instead of performing + * multiple atomic inc() operations. */ 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 +309,10 @@ 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 Mon Dec 11 03:52:41 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13486647 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="jEbyzVmX" Received: from mail-yw1-x112f.google.com (mail-yw1-x112f.google.com [IPv6:2607:f8b0:4864:20::112f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D389FF1 for ; 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bh=J730iItaW8fpD9bcYiCc3WSDtwgBtsyA2Jb0R83edv4=; b=vJvIXCBjz2q8BvRErpk+mIn4L03DabgjXgalQLSxtD4SzYs8ZtCI+g8jkC4Vo6+x0W Va9O3kUm1F5cfxgCXXAswcRswe47mLdCsP3PU7gzQ7/48/gq3vPnUK4qWyyBasfk8fUk r5SZGjVvnKDlRdIqapDIiHU0P/0UJnhFPQ0atUo3r1m6dmcFTtyDpVmiMcfKQHGH+vrP x7tdIqF+iIsPt+M981TAdGW/+qcixRphAY1YjkPjizt/xws0xJraaVsQJsLy2vnRG5w8 bVeAY0+0XTBx/ZxQGejhsjiYKBkpo6dp8LIehk5hbNb9Ve4Vh0bR4l9IZ+R42rKV+VuB TJdA== X-Gm-Message-State: AOJu0YywxVKJDUR2ENxFhSSfTMOzkS5TLSAI8xvWjvp6G/wmoj6iFQ9x eqSfTHlF5+xjKvfL9jP6sZY= X-Google-Smtp-Source: AGHT+IHcK2/Q8KqUlgqgd9YgADevE8eOhbq+FQOnrZxm7i37nZvpcynhBH5Vgt0k8DumJ+fezNSkrA== X-Received: by 2002:a81:8406:0:b0:5d4:2ab1:9f0a with SMTP id u6-20020a818406000000b005d42ab19f0amr2593146ywf.42.1702266800986; Sun, 10 Dec 2023 19:53:20 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id b8-20020a170903228800b001d052d1aaf2sm5411491plh.101.2023.12.10.19.53.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 19:53:20 -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, almasrymina@google.com, liangchen.linux@gmail.com Subject: [PATCH net-next v8 2/4] page_pool: halve BIAS_MAX for multiple user references of a fragment Date: Mon, 11 Dec 2023 11:52:41 +0800 Message-Id: <20231211035243.15774-3-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231211035243.15774-1-liangchen.linux@gmail.com> References: <20231211035243.15774-1-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 Mon Dec 11 03:52:42 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13486648 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="CVkoZ1/E" Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0316F1 for ; Sun, 10 Dec 2023 19:53:27 -0800 (PST) Received: by mail-pj1-x102e.google.com with SMTP id 98e67ed59e1d1-28862fdfb44so2958651a91.0 for ; Sun, 10 Dec 2023 19:53:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702266807; x=1702871607; 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=CVkoZ1/EqOhWB+lBgbfq4Bzh2V1BIROBlPUH5YNmyscLc5gv+b9vza8oMD8xvQw4/U gK6wNkzmnYYx5nUxLv/hCT5W+qLWbeY4cl0rwzKnfFXFF620FX5TVAILKvvlIRDNwZJ9 ZdtbGXhaPnTSu9LGyLzs8fSrbSMoiwHx258deoIrEdr4QYS7UifvS+kTc2eMejSdUJk4 oZI3/wqgKq8KTzJ45QmoJapWALNkzQA5TFb9a66XH5v95Unpz9Ywyq/RI6kbNfce2V2n lgJcoLpCziB+PzPJZNqi+os4lLRCRlJB0CrNoDRuER4fUC2RMZHPWk4YCVz7NvztepVW SM4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702266807; x=1702871607; 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=ryf5OTMvcbpXc6i1df7proUIm67qiSsTgglKA0t8+tiy3PuO1pUH//IwUMftYZEylv CZqlAEltZMzGkdW1zhHNLiOzxudRVtU4MMpwiMALgyM+nEH69rrQXgFLzUF6E7SUgFy5 iuuTz+h2xPqSKgmGSDxVIoo//6firflMkRDv8XQfCXJirEC7e84vwd1Pq9O68QCtsae1 UY2k/3silM/Tuzy+px6tXWGO4glhmt9LHCmYHW15Tag+F9jUs48CXLot5vv+LhgCRoGv 83LEapFVpmqc+kl1pp9EApyrTXIe6Rsjun1viqPwj2cO+vPPo/0ICrtnWGObxyDHG4M+ d4UQ== X-Gm-Message-State: AOJu0Yw6TpxHgStOs0MEIYlNZI025eUigiHG0FthOFZYKQGIiMC7jn3/ O7m4nxLRu/S7cfJXPAxoycgNTK0Rjeo= X-Google-Smtp-Source: AGHT+IF/9zzYT5dBgAhPgi9UwWntEpQIso8WA4BYMk8jEYQTrt8722TIA7PHJFeT1xdLlXRfSo/WOA== X-Received: by 2002:a17:902:d4c5:b0:1d0:91c3:aaf2 with SMTP id o5-20020a170902d4c500b001d091c3aaf2mr1656471plg.25.1702266806761; Sun, 10 Dec 2023 19:53:26 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id b8-20020a170903228800b001d052d1aaf2sm5411491plh.101.2023.12.10.19.53.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 19:53:25 -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, almasrymina@google.com, liangchen.linux@gmail.com Subject: [PATCH net-next v8 3/4] skbuff: Add a function to check if a page belongs to page_pool Date: Mon, 11 Dec 2023 11:52:42 +0800 Message-Id: <20231211035243.15774-4-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231211035243.15774-1-liangchen.linux@gmail.com> References: <20231211035243.15774-1-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 Reviewed-by: Ilias Apalodimas --- 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 Mon Dec 11 03:52:43 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liang Chen X-Patchwork-Id: 13486649 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="jNrt3VrX" Received: from mail-il1-x131.google.com (mail-il1-x131.google.com [IPv6:2607:f8b0:4864:20::131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C971ED for ; Sun, 10 Dec 2023 19:53:35 -0800 (PST) Received: by mail-il1-x131.google.com with SMTP id e9e14a558f8ab-35e70495835so11974565ab.3 for ; Sun, 10 Dec 2023 19:53:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1702266814; x=1702871614; 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=ZVUa6NcsCdWv7jZCGAOsNgtw6R7wscnm5fcwcGKxQ5Q=; b=jNrt3VrXyEOMz9au0o9rE94lonrTXVTRts8PflZ7bG/hFMar+erqgXDk0Ql+d+jBNJ A+JKTC6/F9aB7QzfIcgyqnThLnsqwjCX/EWjvub+9kvZuDzsQqYsQqcc8WatgfjzlO/d vopkLKvpFqruJQS36x76B6S1McUywaES7rlg6gHYl6qvIDaodaUoruxrfCa6nYKUjrOh qT7zp28eIK+fyUJEWYB4Q2zmhYNHZxrx0hQlbBoRcwd1NN1/7JjnHQhuwJixoFZVDBeX Vi2KXotV24IaAMiysGqbF0Gbv3H0kucp/0t6lbzjVs6/Yq3AVWw+41R7FWxLV3OoWhdy fPcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702266814; x=1702871614; 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=ZVUa6NcsCdWv7jZCGAOsNgtw6R7wscnm5fcwcGKxQ5Q=; b=Pz2z9jZVKnNit6wptAhgIjGcYYeyxDOr/yklHz2I9F53+MHgAmF0ZAv/5E1Al1GC9f hxlVWe4LnEQTpBsL0z/Ebq9dKSi3W7QPmdJaFO68v/E7FgMOL1BTKhkcZOZfQcvJJnPr NU/H6gcI6ZfnFXd5/VY9ZguBkf1kDeKjEoNCJ8fXDZ2oUxLNRhiAxSULQEFQ+xHd4kdu ec+1P4AEG2bKgclGyEqcz8YfgANU8U6JNqne6zQSdeAKUh/sIIzhlDriOd/GbQ+Rgs3l k5ckt2xmZAx7vpie3soTvARks3yx1FZDSAxSKw7t5tcu5y7FwBRSkVadXHt3BaEAFNzX MOKg== X-Gm-Message-State: AOJu0Yz2PtZ5RiZI2WZgsAU2pnWnH8Vut8kOFTxS0luyDXVyu5ZjAFsE RpHdcTonEzJTUXSl/NomNW8= X-Google-Smtp-Source: AGHT+IFdjnKcGXA1RGpVDmqmZBCacHeqjUYLhgaJubLPawvL/tu4PXYUQAsrkLCPyQemnmeb07fCSA== X-Received: by 2002:a92:ca4b:0:b0:35d:4f54:a9f0 with SMTP id q11-20020a92ca4b000000b0035d4f54a9f0mr7270958ilo.32.1702266814686; Sun, 10 Dec 2023 19:53:34 -0800 (PST) Received: from localhost.localdomain ([89.187.161.180]) by smtp.gmail.com with ESMTPSA id b8-20020a170903228800b001d052d1aaf2sm5411491plh.101.2023.12.10.19.53.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 10 Dec 2023 19:53:33 -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, almasrymina@google.com, liangchen.linux@gmail.com Subject: [PATCH net-next v8 4/4] skbuff: Optimization of SKB coalescing for page pool Date: Mon, 11 Dec 2023 11:52:43 +0800 Message-Id: <20231211035243.15774-5-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231211035243.15774-1-liangchen.linux@gmail.com> References: <20231211035243.15774-1-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 d0c5e7e6857a..0dc8fab43bef 100644 --- a/include/net/page_pool/helpers.h +++ b/include/net/page_pool/helpers.h @@ -281,6 +281,11 @@ 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;