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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 978C6C433E0 for ; Mon, 18 May 2020 11:56:17 +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 62B4A2065F for ; Mon, 18 May 2020 11:56:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hvkehilX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 62B4A2065F 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]:53018 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jaeNU-0001CG-Hd for qemu-devel@archiver.kernel.org; Mon, 18 May 2020 07:56:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:44884) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jaeMw-0000kw-4m for qemu-devel@nongnu.org; Mon, 18 May 2020 07:55:42 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:22025 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jaeMv-0000SC-B4 for qemu-devel@nongnu.org; Mon, 18 May 2020 07:55:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589802940; 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=kUCUZ9NJwN4WFfrHpcgbGGTP3TYy4s6wVLw1GDd8SZs=; b=hvkehilXn33spmPtZq0GH7CHxB6duSs9h/sZGhGEMDHbSE48tlad3NfQ9O+Xu6WT3Ix1MX 5tDz+5bW+V4Fuv3dun5E5xpvRQN8bBcYqsQQzJeHegHpK57oBPsFNSzPnTYVf/VKd3pkHF P7MteRdY5s9SnrOVpRN4HmMYUbWKk/4= 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-64-_vl_JODRMdmnrbej8Y_UXw-1; Mon, 18 May 2020 07:55:38 -0400 X-MC-Unique: _vl_JODRMdmnrbej8Y_UXw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E21A3800D24; Mon, 18 May 2020 11:55:37 +0000 (UTC) Received: from work-vm (ovpn-112-78.ams2.redhat.com [10.36.112.78]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E1CC1579A5; Mon, 18 May 2020 11:55:36 +0000 (UTC) Date: Mon, 18 May 2020 12:55:34 +0100 From: "Dr. David Alan Gilbert" To: Zhanghailiang Subject: Re: =?utf-8?B?562U5aSNOiBbUEFUQw==?= =?utf-8?Q?H?= 5/6] migration/qemu-file.c: Don't ratelimit a shutdown fd Message-ID: <20200518115534.GD2786@work-vm> References: <1dc261c8dce6421b80071c0eb3528afd@huawei.com> MIME-Version: 1.0 In-Reply-To: <1dc261c8dce6421b80071c0eb3528afd@huawei.com> User-Agent: Mutt/1.13.4 (2020-02-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/17 22:51:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] 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, SPF_PASS=-0.001, T_HK_NAME_DR=0.01, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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: Lukas Straub , qemu-devel , Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Zhanghailiang (zhang.zhanghailiang@huawei.com) wrote: > > This causes the migration thread to hang if we failover during checkpoint. A > > shutdown fd won't cause network traffic anyway. > > > > I'm not quite sure if this modification can take side effect on normal migration process or not, > There are several places calling it. > > Maybe Juan and Dave can help ;) > > > Signed-off-by: Lukas Straub > > --- > > migration/qemu-file.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c index > > 1c3a358a14..0748b5810f 100644 > > --- a/migration/qemu-file.c > > +++ b/migration/qemu-file.c > > @@ -660,7 +660,7 @@ int64_t qemu_ftell(QEMUFile *f) int > > qemu_file_rate_limit(QEMUFile *f) { > > if (f->shutdown) { > > - return 1; > > + return 0; > > } This looks wrong to me; I'd be curious to understand how it's hanging for you. '1' means 'stop what you're doing', 0 means carry on; carrying on with a shutdown fd sounds wrong. If we look at ram.c we have: while ((ret = qemu_file_rate_limit(f)) == 0 || !QSIMPLEQ_EMPTY(&rs->src_page_requests)) { int pages; .... so if it returns '1', as it does at the moment it should cause it to exit the ram_save_iterate loop - which is what we want if it's failing. Thus I think you need to find the actual place it's stuck in this case - I suspect it's repeatedly calling ram_save_iterate and then exiting it, but if that's happening perhaps we're missing a qemu_file_get_error check somewhere. Dave > > if (qemu_file_get_error(f)) { > > return 1; > > -- > > 2.20.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK