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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 0D2BBC3A59D for ; Mon, 19 Aug 2019 10:48:28 +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 D6B5020851 for ; Mon, 19 Aug 2019 10:48:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D6B5020851 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]:47792 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzfD8-0007V5-8f for qemu-devel@archiver.kernel.org; Mon, 19 Aug 2019 06:48:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49882) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzfBu-0006cI-FM for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:47:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hzfBs-0005CZ-5q for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:47:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37510) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hzfBs-0005CE-0Q for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:47:08 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5453D19AD50C for ; Mon, 19 Aug 2019 10:47:07 +0000 (UTC) Received: from redhat.com (unknown [10.36.118.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C126918944; Mon, 19 Aug 2019 10:47:06 +0000 (UTC) From: Juan Quintela To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= In-Reply-To: <20190819095228.GC12960@redhat.com> ("Daniel P. =?utf-8?Q?Ber?= =?utf-8?Q?rang=C3=A9=22's?= message of "Mon, 19 Aug 2019 10:52:28 +0100") References: <20190814020218.1868-1-quintela@redhat.com> <20190814020218.1868-7-quintela@redhat.com> <20190819095228.GC12960@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) Date: Mon, 19 Aug 2019 12:47:03 +0200 Message-ID: <87o90l300o.fsf@trasno.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Mon, 19 Aug 2019 10:47:07 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 6/6] RFH: We lost "connect" events 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: quintela@redhat.com Cc: qemu-devel@nongnu.org, "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 wrote: > On Wed, Aug 14, 2019 at 04:02:18AM +0200, Juan Quintela wrote: >> When we have lots of channels, sometimes multifd migration fails >> with the following error: >>=20 >> Any good ideas? > > In inet_listen_saddr() we call > > if (!listen(slisten, 1)) { > > note the second parameter sets the socket backlog, which is the max > number of pending socket connections we allow. My guess is that the > target QEMU is not accepting incoming connections quickly enough and > thus you hit the limit & the kernel starts dropping the incoming > connections. > > As a quick test, just hack this code to pass a value of 100 and see > if it makes your test reliable. If it does, then we'll need to figure > out a nice way to handle backlog instead of hardcoding it at 1. Nice. With this change I can create 100 channels on a 4 core machine without any trouble (5 tries so far). Previously with 10 channels on the same machine failed around 50% of the time, and 100 channels failed 100% of the time. How can we proceed from here? Thanks, Juan.