From patchwork Tue Feb 16 14:35:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 12090087 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F1EFC433E9 for ; Tue, 16 Feb 2021 14:36:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EA5764E08 for ; Tue, 16 Feb 2021 14:36:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230393AbhBPOgI (ORCPT ); Tue, 16 Feb 2021 09:36:08 -0500 Received: from mail2.protonmail.ch ([185.70.40.22]:58141 "EHLO mail2.protonmail.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230383AbhBPOfs (ORCPT ); Tue, 16 Feb 2021 09:35:48 -0500 Date: Tue, 16 Feb 2021 14:35:02 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail; t=1613486103; bh=PUPLXjpwpkpzqk95FTsck/1hnkmAyZsE+RsTIuWPKnY=; h=Date:To:From:Cc:Reply-To:Subject:In-Reply-To:References:From; b=X0KO8Ega8wHesK00ZIwrSYc9iOEoawjMUnAsj2OQVTRXTg3nbl7hhAH6ud7otDGE8 lzGC2dkmHnpVwn//C+dT4B2Zl1vM9UqccR2ffC974eWvwuE6V0jzpbkXWuTv7sFaB5 /6fIs0IUSb4UhfwKdcR7oLjdACyv5uz4/nIwLeV6HkNQcVPZt+oLVnjCRypUqvlBIz Xn1ogvueiV4Jc0IgofIyv9uy+2lwXhlKxWZMf5QKtdT8GF+zlzzLfnqw7Qzj4rGs/Y rn2npD2AON2S6AvmLgH/054gOofGUgEvEoB8sH+VVE/VG2VWzARUHORXmigLHY37S9 oIGeQRjXPqXsg== To: Magnus Karlsson , =?utf-8?b?QmrDtnJuIFTDtnBl?= =?utf-8?b?bA==?= From: Alexander Lobakin Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Jonathan Lemon , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Paolo Abeni , Eric Dumazet , Xuan Zhuo , Dust Li , Alexander Lobakin , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Reply-To: Alexander Lobakin Subject: [PATCH v5 bpf-next 6/6] xsk: build skb by page (aka generic zerocopy xmit) Message-ID: <20210216143333.5861-7-alobakin@pm.me> In-Reply-To: <20210216143333.5861-1-alobakin@pm.me> References: <20210216143333.5861-1-alobakin@pm.me> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Xuan Zhuo This patch is used to construct skb based on page to save memory copy overhead. This function is implemented based on IFF_TX_SKB_NO_LINEAR. Only the network card priv_flags supports IFF_TX_SKB_NO_LINEAR will use page to directly construct skb. If this feature is not supported, it is still necessary to copy data to construct skb. ---------------- Performance Testing ------------ The test environment is Aliyun ECS server. Test cmd: ``` xdpsock -i eth0 -t -S -s ``` Test result data: size 64 512 1024 1500 copy 1916747 1775988 1600203 1440054 page 1974058 1953655 1945463 1904478 percent 3.0% 10.0% 21.58% 32.3% Signed-off-by: Xuan Zhuo Reviewed-by: Dust Li [ alobakin: - expand subject to make it clearer; - improve skb->truesize calculation; - reserve some headroom in skb for drivers; - tailroom is not needed as skb is non-linear ] Signed-off-by: Alexander Lobakin Acked-by: Magnus Karlsson --- net/xdp/xsk.c | 119 ++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 95 insertions(+), 24 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 143979ea4165..ff7bd06e1241 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -445,6 +445,96 @@ static void xsk_destruct_skb(struct sk_buff *skb) sock_wfree(skb); } +static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, + struct xdp_desc *desc) +{ + struct xsk_buff_pool *pool = xs->pool; + u32 hr, len, offset, copy, copied; + struct sk_buff *skb; + struct page *page; + void *buffer; + int err, i; + u64 addr; + + hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(xs->dev->needed_headroom)); + + skb = sock_alloc_send_skb(&xs->sk, hr, 1, &err); + if (unlikely(!skb)) + return ERR_PTR(err); + + skb_reserve(skb, hr); + + addr = desc->addr; + len = desc->len; + + buffer = xsk_buff_raw_get_data(pool, addr); + offset = offset_in_page(buffer); + addr = buffer - pool->addrs; + + for (copied = 0, i = 0; copied < len; i++) { + page = pool->umem->pgs[addr >> PAGE_SHIFT]; + get_page(page); + + copy = min_t(u32, PAGE_SIZE - offset, len - copied); + skb_fill_page_desc(skb, i, page, offset, copy); + + copied += copy; + addr += copy; + offset = 0; + } + + skb->len += len; + skb->data_len += len; + skb->truesize += pool->unaligned ? len : pool->chunk_size; + + refcount_add(skb->truesize, &xs->sk.sk_wmem_alloc); + + return skb; +} + +static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, + struct xdp_desc *desc) +{ + struct net_device *dev = xs->dev; + struct sk_buff *skb; + + if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) { + skb = xsk_build_skb_zerocopy(xs, desc); + if (IS_ERR(skb)) + return skb; + } else { + u32 hr, tr, len; + void *buffer; + int err; + + hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom)); + tr = dev->needed_tailroom; + len = desc->len; + + skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); + if (unlikely(!skb)) + return ERR_PTR(err); + + skb_reserve(skb, hr); + skb_put(skb, len); + + buffer = xsk_buff_raw_get_data(xs->pool, desc->addr); + err = skb_store_bits(skb, 0, buffer, len); + if (unlikely(err)) { + kfree_skb(skb); + return ERR_PTR(err); + } + } + + skb->dev = dev; + skb->priority = xs->sk.sk_priority; + skb->mark = xs->sk.sk_mark; + skb_shinfo(skb)->destructor_arg = (void *)(long)desc->addr; + skb->destructor = xsk_destruct_skb; + + return skb; +} + static int xsk_generic_xmit(struct sock *sk) { struct xdp_sock *xs = xdp_sk(sk); @@ -454,56 +544,37 @@ static int xsk_generic_xmit(struct sock *sk) struct sk_buff *skb; unsigned long flags; int err = 0; - u32 hr, tr; mutex_lock(&xs->mutex); if (xs->queue_id >= xs->dev->real_num_tx_queues) goto out; - hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(xs->dev->needed_headroom)); - tr = xs->dev->needed_tailroom; - while (xskq_cons_peek_desc(xs->tx, &desc, xs->pool)) { - char *buffer; - u64 addr; - u32 len; - if (max_batch-- == 0) { err = -EAGAIN; goto out; } - len = desc.len; - skb = sock_alloc_send_skb(sk, hr + len + tr, 1, &err); - if (unlikely(!skb)) + skb = xsk_build_skb(xs, &desc); + if (IS_ERR(skb)) { + err = PTR_ERR(skb); goto out; + } - skb_reserve(skb, hr); - skb_put(skb, len); - - addr = desc.addr; - buffer = xsk_buff_raw_get_data(xs->pool, addr); - err = skb_store_bits(skb, 0, buffer, len); /* This is the backpressure mechanism for the Tx path. * Reserve space in the completion queue and only proceed * if there is space in it. This avoids having to implement * any buffering in the Tx path. */ spin_lock_irqsave(&xs->pool->cq_lock, flags); - if (unlikely(err) || xskq_prod_reserve(xs->pool->cq)) { + if (xskq_prod_reserve(xs->pool->cq)) { spin_unlock_irqrestore(&xs->pool->cq_lock, flags); kfree_skb(skb); goto out; } spin_unlock_irqrestore(&xs->pool->cq_lock, flags); - skb->dev = xs->dev; - skb->priority = sk->sk_priority; - skb->mark = sk->sk_mark; - skb_shinfo(skb)->destructor_arg = (void *)(long)desc.addr; - skb->destructor = xsk_destruct_skb; - err = __dev_direct_xmit(skb, xs->queue_id); if (err == NETDEV_TX_BUSY) { /* Tell user-space to retry the send */