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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 E524CC433DB for ; Mon, 8 Feb 2021 21:54:39 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 447C464E54 for ; Mon, 8 Feb 2021 21:54:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 447C464E54 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:47934 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l9EUQ-0001Aa-1I for qemu-devel@archiver.kernel.org; Mon, 08 Feb 2021 16:54:38 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57124) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l99fi-0008My-Dw for qemu-devel@nongnu.org; Mon, 08 Feb 2021 11:45:59 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:27445) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l99fV-00068m-2g for qemu-devel@nongnu.org; Mon, 08 Feb 2021 11:45:57 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612802742; 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=7Nrf+H5C3SUm9QqX+jcA/JZhGMHMJ//sy1WRNOeat2A=; b=BiB4FMkNOHdyqeZTbgc6xtcF+wIPscWsVfNGdwr1Ie+anu3Y/hDKgN2ofUaJffLKGvNUBF T03JBr6/Y4+ZrZ96hI+XxtIGzfmuzpnTEscNTJNVZuknAvBpDNgF7wG5aYD8q0uXAs8M6e QjmKRqVT7WGw381jlHYc61TtIntJYFU= 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-335-t2kcsIlNOni2b3hzkTDrig-1; Mon, 08 Feb 2021 11:45:24 -0500 X-MC-Unique: t2kcsIlNOni2b3hzkTDrig-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BB1A61005501; Mon, 8 Feb 2021 16:45:23 +0000 (UTC) Received: from [10.3.114.150] (ovpn-114-150.phx2.redhat.com [10.3.114.150]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4B4615D743; Mon, 8 Feb 2021 16:45:23 +0000 (UTC) Subject: Re: [PATCH v2] qemu-nbd: Use SOMAXCONN for socket listen() backlog To: =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= References: <20210205185705.1502071-1-eblake@redhat.com> <20210208100004.GD1141037@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Mon, 8 Feb 2021 10:45:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210208100004.GD1141037@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.57, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.265, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, rjones@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2/8/21 4:00 AM, Daniel P. Berrangé wrote: > On Fri, Feb 05, 2021 at 12:57:05PM -0600, Eric Blake wrote: >> Our default of a backlog of 1 connection is rather puny, particularly >> for scenarios where we expect multiple listeners to connect (such as >> qemu-nbd -e X). This is especially important for Unix sockets, as a >> definite benefit to clients: at least on Linux, a client trying to >> connect to a Unix socket with a backlog gets an EAGAIN failure with no >> way to poll() for when the backlog is no longer present short of >> sleeping an arbitrary amount of time before retrying. >> >> See https://bugzilla.redhat.com/1925045 for a demonstration of where >> our low backlog prevents libnbd from connecting as many parallel >> clients as it wants. >> >> Reported-by: Richard W.M. Jones >> Signed-off-by: Eric Blake >> --- >> >> v2: target the correct API used by qemu-nbd, rather than an unrelated >> legacy wrapper [Dan] >> >> qemu-nbd.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/qemu-nbd.c b/qemu-nbd.c >> index 608c63e82a25..cd20ee73be19 100644 >> --- a/qemu-nbd.c >> +++ b/qemu-nbd.c >> @@ -965,7 +965,8 @@ int main(int argc, char **argv) >> server = qio_net_listener_new(); >> if (socket_activation == 0) { >> saddr = nbd_build_socket_address(sockpath, bindto, port); >> - if (qio_net_listener_open_sync(server, saddr, 1, &local_err) < 0) { >> + if (qio_net_listener_open_sync(server, saddr, SOMAXCONN, >> + &local_err) < 0) { > > This addresses qemu-nbd, but surely we want to be consistent with the > QMP nbd-server-start impl too, in blockdev-nbd.c > Good point, I'll send v3. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org