From patchwork Mon May 22 07:39:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arseniy Krasnov X-Patchwork-Id: 13249957 X-Patchwork-Delegate: kuba@kernel.org Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FC92BE4B for ; Mon, 22 May 2023 07:45:00 +0000 (UTC) Received: from mx.sberdevices.ru (mx.sberdevices.ru [45.89.227.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B86D7B9; Mon, 22 May 2023 00:44:58 -0700 (PDT) Received: from s-lin-edge02.sberdevices.ru (localhost [127.0.0.1]) by mx.sberdevices.ru (Postfix) with ESMTP id 670A75FD58; Mon, 22 May 2023 10:44:56 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sberdevices.ru; s=mail; t=1684741496; bh=tL2E1Y90S5bBkA16ZM0oXYsz18KCFk1Zn9JPdTBbPT8=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; b=FkbuJcet7/EeE21YdTm700Ur3nc8dAzhkK906t8tCzyoOguXcRwW/XJqWGWzso/TB gslDKyJwpgtxjlNA7yHGVYFvCnieFVvwizU9vcM3rEjJ2eeoph0wycEBZpFDF4y6Qb B61Y67cvLpQ6Y0ipqbOCxO6nzBvvW974Me1357J0ui5NO9iDN+/d4/haePisxdvnVu HrbYi9S7FQpHZeqm3xYOJ2jYiPHsrl0hFsSNYH1OYoKecvivVI+kWsjdoZfY225rTl wqDgvBy3WSJWpu6WjaDmRiDip3a2uCyprXUYmcd+lFk2ZZbQAxNFLOxCw2y7u8+dyx cn3POZlU5uIfg== Received: from S-MS-EXCH01.sberdevices.ru (S-MS-EXCH01.sberdevices.ru [172.16.1.4]) by mx.sberdevices.ru (Postfix) with ESMTP; Mon, 22 May 2023 10:44:56 +0300 (MSK) 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: , , , , , , , Arseniy Krasnov Subject: [RFC PATCH v3 14/17] docs: net: description of MSG_ZEROCOPY for AF_VSOCK Date: Mon, 22 May 2023 10:39:47 +0300 Message-ID: <20230522073950.3574171-15-AVKrasnov@sberdevices.ru> X-Mailer: git-send-email 2.35.0 In-Reply-To: <20230522073950.3574171-1-AVKrasnov@sberdevices.ru> References: <20230522073950.3574171-1-AVKrasnov@sberdevices.ru> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH02.sberdevices.ru (172.16.1.5) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2023/05/22 04:49:00 #21364689 X-KSMG-AntiVirus-Status: Clean, skipped X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: kuba@kernel.org X-Patchwork-State: RFC This adds description of MSG_ZEROCOPY flag support for AF_VSOCK type of socket. Signed-off-by: Arseniy Krasnov --- Documentation/networking/msg_zerocopy.rst | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/Documentation/networking/msg_zerocopy.rst b/Documentation/networking/msg_zerocopy.rst index b3ea96af9b49..34bc7ff411ce 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 +175,7 @@ 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). 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 @@ -201,6 +202,7 @@ undefined, bar for ee_code, as discussed below. printf("completed: %u..%u\n", serr->ee_info, serr->ee_data); +For VSOCK socket, cmsg_level will be SOL_VSOCK and cmsg_type will be 0. Deferred copies ~~~~~~~~~~~~~~~ @@ -235,12 +237,15 @@ 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 +259,6 @@ 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.