From patchwork Tue Apr 4 00:40:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 13198952 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 475DEC76188 for ; Tue, 4 Apr 2023 00:43:18 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pjUkf-0001uo-7G; Mon, 03 Apr 2023 20:42:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pjUkc-0001uW-MS for qemu-devel@nongnu.org; Mon, 03 Apr 2023 20:42:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pjUjH-0005tz-OX for qemu-devel@nongnu.org; Mon, 03 Apr 2023 20:42:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680568854; 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; bh=Ghimxv6q2GZqhNn00GP/SmdJfIdYbYnsMJqJgbJ/IwU=; b=dRZirAlMQStDdG548Giec02rREYKCNv/ncLtxeUSVj/UkiTq0ScM1Vw8TntMPAaMwcWC5f BtcnYVXMz2CGUv+hqpR0zeQ/zHHLRLY07la5JjUsc0uJ5ZPBMMtsxFCp21Y+hy15di51L/ iUHkKSOzyv9Kg3D+5pA7ugIZYlWL9dk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-584-67eh01FRNaWBv_myHO-c0w-1; Mon, 03 Apr 2023 20:40:51 -0400 X-MC-Unique: 67eh01FRNaWBv_myHO-c0w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1EEC3101A550; Tue, 4 Apr 2023 00:40:51 +0000 (UTC) Received: from green.redhat.com (unknown [10.2.16.110]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3AF522027040; Tue, 4 Apr 2023 00:40:50 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Cc: Florian Westphal , Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org (open list:Network Block Dev...) Subject: [PATCH v2 for 8.0?] nbd/server: Request TCP_NODELAY Date: Mon, 3 Apr 2023 19:40:47 -0500 Message-Id: <20230404004047.142086-1-eblake@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Nagle's algorithm adds latency in order to reduce network packet overhead on small packets. But when we are already using corking to merge smaller packets into transactional requests, the extra delay from TCP defaults just gets in the way (see recent commit bd2cd4a4). For reference, qemu as an NBD client already requests TCP_NODELAY (see nbd_connect() in nbd/client-connection.c); as does libnbd as a client [1], and nbdkit as a server [2]. Furthermore, the NBD spec recommends the use of TCP_NODELAY [3]. [1] https://gitlab.com/nbdkit/libnbd/-/blob/a48a1142/generator/states-connect.c#L39 [2] https://gitlab.com/nbdkit/nbdkit/-/blob/45b72f5b/server/sockets.c#L430 [3] https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md#protocol-phases CC: Florian Westphal Signed-off-by: Eric Blake Message-Id: <20230327192947.1324372-1-eblake@redhat.com> Reviewed-by: Philippe Mathieu-Daudé Acked-by: Paolo Bonzini --- v2 fix typo, enhance commit message Given that corking made it in through Kevin's tree for 8.0-rc2 but this one did not, but I didn't get any R-b, is there any objection to me doing a pull request to get this into 8.0-rc3? nbd/server.c | 1 + 1 file changed, 1 insertion(+) base-commit: efcd0ec14b0fe9ee0ee70277763b2d538d19238d diff --git a/nbd/server.c b/nbd/server.c index 848836d4140..3d8d0d81df2 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -2758,6 +2758,7 @@ void nbd_client_new(QIOChannelSocket *sioc, } client->tlsauthz = g_strdup(tlsauthz); client->sioc = sioc; + qio_channel_set_delay(QIO_CHANNEL(sioc), false); object_ref(OBJECT(client->sioc)); client->ioc = QIO_CHANNEL(sioc); object_ref(OBJECT(client->ioc));