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 44FFCC3A59D for ; Mon, 19 Aug 2019 10:51:54 +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 1A38720851 for ; Mon, 19 Aug 2019 10:51:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A38720851 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]:47840 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzfGT-00016l-0W for qemu-devel@archiver.kernel.org; Mon, 19 Aug 2019 06:51:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50765) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1hzfFf-0000fm-PJ for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:51:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hzfFe-0007oV-O1 for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:51:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36960) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hzfFe-0007o4-IE for qemu-devel@nongnu.org; Mon, 19 Aug 2019 06:51:02 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 9C86E3003AFE for ; Mon, 19 Aug 2019 10:51:01 +0000 (UTC) Received: from redhat.com (unknown [10.36.118.76]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2C95158C99; Mon, 19 Aug 2019 10:51:00 +0000 (UTC) From: Juan Quintela To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= In-Reply-To: <20190819104916.GG12960@redhat.com> ("Daniel P. =?utf-8?Q?Ber?= =?utf-8?Q?rang=C3=A9=22's?= message of "Mon, 19 Aug 2019 11:49:16 +0100") References: <20190814020218.1868-1-quintela@redhat.com> <20190814020218.1868-7-quintela@redhat.com> <20190819095228.GC12960@redhat.com> <87pnl1301v.fsf@trasno.org> <20190819104916.GG12960@redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) Date: Mon, 19 Aug 2019 12:50:58 +0200 Message-ID: <87k1b92zu5.fsf@trasno.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Mon, 19 Aug 2019 10:51:01 +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 Mon, Aug 19, 2019 at 12:46:20PM +0200, Juan Quintela wrote: >> 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. >>=20 >> Nice. >>=20 >> With this change I can create 100 channels on a 4 core machine without >> any trouble. >>=20 >> How can we proceed from here? > > I don't think we want to expose this in the QAPI schema for the socket > address, since the correct value is really something that QEMU should > figure out based on usage context. > > Thus, I think we'll have to make it an explicit parameter to the > qio_channel_socket_listen_{sync,async} APIs, and socket_listen() > and inet_listen_saddr(), etc. Then the migration code can pass in > a sensible value based on multifd usage. ok with me. I will give it a try. Thanks for the tip. Later, Juan.