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=-15.0 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 D9955C433DB for ; Fri, 5 Feb 2021 09:57:28 +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 4E84E64FB9 for ; Fri, 5 Feb 2021 09:57:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4E84E64FB9 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]:38814 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l7xri-0006KP-R2 for qemu-devel@archiver.kernel.org; Fri, 05 Feb 2021 04:57:26 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:41178) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l7xqO-0005J9-Nx for qemu-devel@nongnu.org; Fri, 05 Feb 2021 04:56:04 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:50071) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1l7xqM-0007n4-HJ for qemu-devel@nongnu.org; Fri, 05 Feb 2021 04:56:04 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612518961; h=from:from:reply-to: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=hf20HDAPhuKrrjznAulfNd7rNt368j1XovbwPnCzYd0=; b=EjufZQqMwcWnpYuGn6PNWRYsxPuCwl912g23aabxF2DRM/yLkaWAjtsbxmgZdejUCrpfB2 EUBMvssUPryqPDujJDYOiiiu7kOy4I1FIvfStARR4HucINbtW+3s0D+wHVT/6FVC9yToae xQF7SIMLfoA0r0DkN8lekwtcv0WjHJw= 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-247-iER1bFDfOOekLc5GH-UgZQ-1; Fri, 05 Feb 2021 04:55:59 -0500 X-MC-Unique: iER1bFDfOOekLc5GH-UgZQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ACB9D18A083A; Fri, 5 Feb 2021 09:55:58 +0000 (UTC) Received: from redhat.com (ovpn-114-212.ams2.redhat.com [10.36.114.212]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2AB441050E; Fri, 5 Feb 2021 09:55:51 +0000 (UTC) Date: Fri, 5 Feb 2021 09:55:48 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Eric Blake Subject: Re: [PATCH] sockets: Use SOMAXCONN for Unix socket listen() Message-ID: <20210205095548.GC908621@redhat.com> References: <20210204222018.1432848-1-eblake@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210204222018.1432848-1-eblake@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.351, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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=ham 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Gerd Hoffmann , 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 Thu, Feb 04, 2021 at 04:20:18PM -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). For Unix sockets, there's no real harm in supporting > a larger backlog, and a definite benefit to the 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 > --- > util/qemu-sockets.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c > index 8af0278f15c6..a7573e9f0fda 100644 > --- a/util/qemu-sockets.c > +++ b/util/qemu-sockets.c > @@ -1059,7 +1059,7 @@ int unix_listen(const char *str, Error **errp) > > saddr = g_new0(UnixSocketAddress, 1); > saddr->path = g_strdup(str); > - sock = unix_listen_saddr(saddr, 1, errp); > + sock = unix_listen_saddr(saddr, SOMAXCONN, errp); > qapi_free_UnixSocketAddress(saddr); > return sock; > } This method is a legacy back compat function, only used by the QEMU guest agent, so this can't explain the NBD problems, which use the QIONetListener class. IOW, the problem is in the qemu-nbd.c / blockdev-nbd.c code I believe Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|