From mboxrd@z Thu Jan 1 00:00:00 1970 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 65208C76195 for ; Mon, 27 Mar 2023 11:45:37 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pglHp-0004X0-7Q; Mon, 27 Mar 2023 07:45:17 -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 1pglHg-0004WE-SD for qemu-devel@nongnu.org; Mon, 27 Mar 2023 07:45:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pglHe-0006uM-Md for qemu-devel@nongnu.org; Mon, 27 Mar 2023 07:45:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1679917505; 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: in-reply-to:in-reply-to:references:references; bh=MdxuTfiEge2qhdm7VL00BR0pb4YGRhj0lDv3HU7Ux48=; b=OAcE+/bB7CcFS1pWD4CrX41bF6/6UMJX4Lz4HgFDvwQWMgYq3KyurlC6t4cnm6wquP9h8g NUHXMi73QKiqvOf4LspwXTmUWuLwq6aY+fxom5zyhe0+q4Fa/paRFsWmg/j6T8b6iVUdKa 6oyQ35u2EneNHiMaH3ibISk2kPHdpqk= 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-369-OeZWqPUeOUmyPAaznRl7Yg-1; Mon, 27 Mar 2023 07:45:02 -0400 X-MC-Unique: OeZWqPUeOUmyPAaznRl7Yg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 90A98884342; Mon, 27 Mar 2023 11:45:01 +0000 (UTC) Received: from redhat.com (unknown [10.39.194.191]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4F4B7C15BA0; Mon, 27 Mar 2023 11:45:00 +0000 (UTC) Date: Mon, 27 Mar 2023 13:44:59 +0200 From: Kevin Wolf To: Florian Westphal Cc: qemu-block@nongnu.org, eblake@redhat.com, vsementsov@yandex-team.ru, qemu-devel@nongnu.org Subject: Re: [PATCH 1/1] nbd/server: push pending frames after sending reply Message-ID: References: <20230324104720.2498-1-fw@strlen.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230324104720.2498-1-fw@strlen.de> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@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=ham 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 Am 24.03.2023 um 11:47 hat Florian Westphal geschrieben: > qemu-nbd doesn't set TCP_NODELAY on the tcp socket. > > Kernel waits for more data and avoids transmission of small packets. > Without TLS this is barely noticeable, but with TLS this really shows. > > Booting a VM via qemu-nbd on localhost (with tls) takes more than > 2 minutes on my system. tcpdump shows frequent wait periods, where no > packets get sent for a 40ms period. > > Add explicit (un)corking when processing (and responding to) requests. > "TCP_CORK, &zero" after earlier "CORK, &one" will flush pending data. > > VM Boot time: > main: no tls: 23s, with tls: 2m45s > patched: no tls: 14s, with tls: 15s > > VM Boot time, qemu-nbd via network (same lan): > main: no tls: 18s, with tls: 1m50s > patched: no tls: 17s, with tls: 18s > > Future optimization: if we could detect if there is another pending > request we could defer the uncork operation because more data would be > appended. > > Signed-off-by: Florian Westphal Thanks, applied to the block branch. Kevin