From patchwork Tue Oct 10 19:15:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arseniy Krasnov X-Patchwork-Id: 13415901 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 021E2CD8CB5 for ; Tue, 10 Oct 2023 19:23:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344051AbjJJTXW (ORCPT ); Tue, 10 Oct 2023 15:23:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234422AbjJJTXD (ORCPT ); Tue, 10 Oct 2023 15:23:03 -0400 Received: from mx1.sberdevices.ru (mx1.sberdevices.ru [37.18.73.165]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA3E811C; Tue, 10 Oct 2023 12:22:49 -0700 (PDT) Received: from p-infra-ksmg-sc-msk01 (localhost [127.0.0.1]) by mx1.sberdevices.ru (Postfix) with ESMTP id 44CA0100011; Tue, 10 Oct 2023 22:22:47 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.sberdevices.ru 44CA0100011 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=salutedevices.com; s=mail; t=1696965767; bh=2q6PSRggf6vem+NLKmcewZXqkO+52GMU/I8fUbkPVOA=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:From; b=tLmNCdc19uA9Jd9ntnGd/48RoJGlWiWC43ilEFfWNS441TKtYa4Xs+eARlEhgfKuc LyphvDFbwiUYoFoWBdrhix+uj8m/qEdQg3GOA906gR8lgogO2/4mVIGCk+Tv7rBUz0 jRRsdoc71RJvdZZNnydCv7F1gAifBYYwCsq8brpPb1ouAkt7d/eapfbpAkGCRKju8H E5kMhaLhLZ43VKydRASiIkxyItwGmLrQ4/a1lz5WCUtJFU8OJLMKB5wfOLyOeKTc1u 79+GGScdx34YCTskgm7LaltQiDcQ3JjJPO6QtTlM9fHMNnouInaNYJpo6W9ff9xtgf T44LQ8xVajyNQ== Received: from p-i-exch-sc-m01.sberdevices.ru (p-i-exch-sc-m01.sberdevices.ru [172.16.192.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.sberdevices.ru (Postfix) with ESMTPS; Tue, 10 Oct 2023 22:22:47 +0300 (MSK) Received: from localhost.localdomain (100.64.160.123) by p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Tue, 10 Oct 2023 22:22:46 +0300 From: Arseniy Krasnov To: Stefan Hajnoczi , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "Michael S. Tsirkin" , Jason Wang , Bobby Eshleman CC: , , , , , , Subject: [PATCH net-next v4 09/12] docs: net: description of MSG_ZEROCOPY for AF_VSOCK Date: Tue, 10 Oct 2023 22:15:21 +0300 Message-ID: <20231010191524.1694217-10-avkrasnov@salutedevices.com> X-Mailer: git-send-email 2.35.0 In-Reply-To: <20231010191524.1694217-1-avkrasnov@salutedevices.com> References: <20231010191524.1694217-1-avkrasnov@salutedevices.com> MIME-Version: 1.0 X-Originating-IP: [100.64.160.123] X-ClientProxiedBy: p-i-exch-sc-m02.sberdevices.ru (172.16.192.103) To p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) X-KSMG-Rule-ID: 10 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Lua-Profiles: 180515 [Oct 10 2023] X-KSMG-AntiSpam-Version: 6.0.0.2 X-KSMG-AntiSpam-Envelope-From: avkrasnov@salutedevices.com X-KSMG-AntiSpam-Rate: 0 X-KSMG-AntiSpam-Status: not_detected X-KSMG-AntiSpam-Method: none X-KSMG-AntiSpam-Auth: dkim=none X-KSMG-AntiSpam-Info: LuaCore: 536 536 1ae19c7800f69da91432b5e67ed4a00b9ade0d03, {Tracking_from_domain_doesnt_match_to}, 127.0.0.199:7.1.2;salutedevices.com:7.1.1;p-i-exch-sc-m01.sberdevices.ru:7.1.1,5.0.1;100.64.160.123:7.1.2;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1, FromAlignment: s, ApMailHostAddress: 100.64.160.123 X-MS-Exchange-Organization-SCL: -1 X-KSMG-AntiSpam-Interceptor-Info: scan successful X-KSMG-AntiPhishing: Clean X-KSMG-LinksScanning: Clean X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 2.0.1.6960, bases: 2023/10/10 16:15:00 #22148151 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org This adds description of MSG_ZEROCOPY flag support for AF_VSOCK type of socket. Signed-off-by: Arseniy Krasnov Reviewed-by: Stefano Garzarella --- Documentation/networking/msg_zerocopy.rst | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst index b3ea96af9b49..78fb70e748b7 100644 --- a/Documentation/networking/msg_zerocopy.rst +++ b/Documentation/networking/msg_zerocopy.rst @@ -7,7 +7,8 @@ Intro ===== The MSG_ZEROCOPY flag enables copy avoidance for socket send calls. -The feature is currently implemented for TCP and UDP sockets. +The feature is currently implemented for TCP, UDP and VSOCK (with +virtio transport) sockets. Opportunity and Caveats @@ -174,7 +175,9 @@ read_notification() call in the previous snippet. A notification is encoded in the standard error format, sock_extended_err. The level and type fields in the control data are protocol family -specific, IP_RECVERR or IPV6_RECVERR. +specific, IP_RECVERR or IPV6_RECVERR (for TCP or UDP socket). +For VSOCK socket, cmsg_level will be SOL_VSOCK and cmsg_type will be +VSOCK_RECVERR. Error origin is the new type SO_EE_ORIGIN_ZEROCOPY. ee_errno is zero, as explained before, to avoid blocking read and write system calls on @@ -235,12 +238,15 @@ Implementation Loopback -------- +For TCP and UDP: Data sent to local sockets can be queued indefinitely if the receive process does not read its socket. Unbound notification latency is not acceptable. For this reason all packets generated with MSG_ZEROCOPY that are looped to a local socket will incur a deferred copy. This includes looping onto packet sockets (e.g., tcpdump) and tun devices. +For VSOCK: +Data path sent to local sockets is the same as for non-local sockets. Testing ======= @@ -254,3 +260,6 @@ instance when run with msg_zerocopy.sh between a veth pair across namespaces, the test will not show any improvement. For testing, the loopback restriction can be temporarily relaxed by making skb_orphan_frags_rx identical to skb_orphan_frags. + +For VSOCK type of socket example can be found in +tools/testing/vsock/vsock_test_zerocopy.c.