From patchwork Wed Apr 22 16:08:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 220759 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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS 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 E30DBC55185 for ; Wed, 22 Apr 2020 16:08:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C2F7E2098B for ; Wed, 22 Apr 2020 16:08:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="X+LYxmOy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726935AbgDVQIO (ORCPT ); Wed, 22 Apr 2020 12:08:14 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:30554 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726928AbgDVQIN (ORCPT ); Wed, 22 Apr 2020 12:08:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587571691; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZzzjCBq9WyI3Bb6b0nAFkEUdPjhrJ6l3Fs8nfiWFreM=; b=X+LYxmOyXGd/uq9hkPRae1weuoIDKnLuqXi3P4Svw5gzy9QSzougwbc2XXTLEN4LNoNk0e /8mtBqoSTqDc2W12r3dFer+2a/mArw+2PD9MqFAcCI78OQpL4kHuMUo+eKgxOAnvjNmI9D B4LKB4QRQ8Ng5td06KjyCX2vQHZEGpA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-455-VXFCodS9NfO1G-hRFQdmZA-1; Wed, 22 Apr 2020 12:08:05 -0400 X-MC-Unique: VXFCodS9NfO1G-hRFQdmZA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 326F613FC; Wed, 22 Apr 2020 16:08:03 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.3]) by smtp.corp.redhat.com (Postfix) with ESMTP id 91C666084C; Wed, 22 Apr 2020 16:08:02 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id B826130000272; Wed, 22 Apr 2020 18:08:01 +0200 (CEST) Subject: [PATCH net-next 08/33] xdp: cpumap redirect use frame_sz and increase skb_tailroom From: Jesper Dangaard Brouer To: sameehj@amazon.com Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, bpf@vger.kernel.org, zorik@amazon.com, akiyano@amazon.com, gtzalik@amazon.com, =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Daniel Borkmann , Alexei Starovoitov , John Fastabend , Alexander Duyck , Jeff Kirsher , David Ahern , Willem de Bruijn , Ilias Apalodimas , Lorenzo Bianconi , Saeed Mahameed , steffen.klassert@secunet.com Date: Wed, 22 Apr 2020 18:08:01 +0200 Message-ID: <158757168168.1370371.11510167625755235041.stgit@firesoul> In-Reply-To: <158757160439.1370371.13213378122947426220.stgit@firesoul> References: <158757160439.1370371.13213378122947426220.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Knowing the memory size backing the packet/xdp_frame data area, and knowing it already have reserved room for skb_shared_info, simplifies using build_skb significantly. With this change we no-longer lie about the SKB truesize, but more importantly a significant larger skb_tailroom is now provided, e.g. when drivers uses a full PAGE_SIZE. This extra tailroom (in linear area) can be used by the network stack when coalescing SKBs (e.g. in skb_try_coalesce, see TCP cases where tcp_queue_rcv() can 'eat' skb). Signed-off-by: Jesper Dangaard Brouer --- kernel/bpf/cpumap.c | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-) diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c index 70f71b154fa5..9c777ac4d4bd 100644 --- a/kernel/bpf/cpumap.c +++ b/kernel/bpf/cpumap.c @@ -162,25 +162,10 @@ static struct sk_buff *cpu_map_build_skb(struct bpf_cpu_map_entry *rcpu, /* Part of headroom was reserved to xdpf */ hard_start_headroom = sizeof(struct xdp_frame) + xdpf->headroom; - /* build_skb need to place skb_shared_info after SKB end, and - * also want to know the memory "truesize". Thus, need to - * know the memory frame size backing xdp_buff. - * - * XDP was designed to have PAGE_SIZE frames, but this - * assumption is not longer true with ixgbe and i40e. It - * would be preferred to set frame_size to 2048 or 4096 - * depending on the driver. - * frame_size = 2048; - * frame_len = frame_size - sizeof(*xdp_frame); - * - * Instead, with info avail, skb_shared_info in placed after - * packet len. This, unfortunately fakes the truesize. - * Another disadvantage of this approach, the skb_shared_info - * is not at a fixed memory location, with mixed length - * packets, which is bad for cache-line hotness. + /* Memory size backing xdp_frame data already have reserved + * room for build_skb to place skb_shared_info in tailroom. */ - frame_size = SKB_DATA_ALIGN(xdpf->len + hard_start_headroom) + - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + frame_size = xdpf->frame_sz; pkt_data_start = xdpf->data - hard_start_headroom; skb = build_skb_around(skb, pkt_data_start, frame_size);