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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id E8EB9C77B7A for ; Wed, 31 May 2023 12:16:54 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q4Kk7-0004UO-0e; Wed, 31 May 2023 08:15:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q4Kk5-0004U6-4h for qemu-devel@nongnu.org; Wed, 31 May 2023 08:15:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q4Kk1-00085n-VJ for qemu-devel@nongnu.org; Wed, 31 May 2023 08:15:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685535349; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3pV/UV4Kb9xVrfXn8pAOVGn5RFKKAUPsu7OGq9tUlGM=; b=VgGvufyg8xLENgcTzNiTYMrARA9Z+tbmIyv5PRfj6H+f2TbqJwrSAYjWi+VfHU+d2t7Q19 6efRX7HI8Yj7wa09EuyLlU7uX78PX+O2H1SuuLw4ldNhsWfNyvPjr5Jayn416fiuVZSbPa HXn75lPSK4IgQXgSDAd4WCrpDlfg/7s= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-120-z8pIQbhYMSOvC88dcKEJgA-1; Wed, 31 May 2023 08:15:46 -0400 X-MC-Unique: z8pIQbhYMSOvC88dcKEJgA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C3B71185A794; Wed, 31 May 2023 12:15:45 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.177]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 629C8C154D7; Wed, 31 May 2023 12:15:43 +0000 (UTC) Date: Wed, 31 May 2023 13:15:39 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Fabiano Rosas , qemu-devel@nongnu.org, qemu-block@nongnu.org, Paolo Bonzini , Thomas Huth , John Snow , Li Zhijian , Juan Quintela , Stefan Hajnoczi , Zhang Chen , Laurent Vivier Subject: Re: [PATCH v2 4/6] tests/qtest: make more migration pre-copy scenarios run non-live Message-ID: References: <20230421171411.566300-1-berrange@redhat.com> <20230421171411.566300-5-berrange@redhat.com> <87jzy1ro3z.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.163, 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_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, May 26, 2023 at 06:58:45PM +0100, Daniel P. Berrangé wrote: > On Mon, Apr 24, 2023 at 06:01:36PM -0300, Fabiano Rosas wrote: > > Daniel P. Berrangé writes: > > > > > There are 27 pre-copy live migration scenarios being tested. In all of > > > these we force non-convergance and run for one iteration, then let it > > > converge and wait for completion during the second (or following) > > > iterations. At 3 mbps bandwidth limit the first iteration takes a very > > > long time (~30 seconds). > > > > > > While it is important to test the migration passes and convergance > > > logic, it is overkill to do this for all 27 pre-copy scenarios. The > > > TLS migration scenarios in particular are merely exercising different > > > code paths during connection establishment. > > > > > > To optimize time taken, switch most of the test scenarios to run > > > non-live (ie guest CPUs paused) with no bandwidth limits. This gives > > > a massive speed up for most of the test scenarios. > > > > > > For test coverage the following scenarios are unchanged > > > > > > * Precopy with UNIX sockets > > > * Precopy with UNIX sockets and dirty ring tracking > > > * Precopy with XBZRLE > > > * Precopy with multifd > > > > > > Signed-off-by: Daniel P. Berrangé > > > --- > > > tests/qtest/migration-test.c | 60 ++++++++++++++++++++++++++++++------ > > > 1 file changed, 50 insertions(+), 10 deletions(-) > > > > > > diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c > > > index 6492ffa7fe..40d0f75480 100644 > > > --- a/tests/qtest/migration-test.c > > > +++ b/tests/qtest/migration-test.c > > > @@ -568,6 +568,9 @@ typedef struct { > > > MIG_TEST_FAIL_DEST_QUIT_ERR, > > > } result; > > > > > > + /* Whether the guest CPUs should be running during migration */ > > > + bool live; > > > + > > > /* Postcopy specific fields */ > > > void *postcopy_data; > > > bool postcopy_preempt; > > > @@ -1324,8 +1327,6 @@ static void test_precopy_common(MigrateCommon *args) > > > return; > > > } > > > > > > - migrate_ensure_non_converge(from); > > > - > > > if (args->start_hook) { > > > data_hook = args->start_hook(from, to); > > > } > > > @@ -1335,6 +1336,31 @@ static void test_precopy_common(MigrateCommon *args) > > > wait_for_serial("src_serial"); > > > } > > > > > > + if (args->live) { > > > + /* > > > + * Testing live migration, we want to ensure that some > > > + * memory is re-dirtied after being transferred, so that > > > + * we exercise logic for dirty page handling. We achieve > > > + * this with a ridiculosly low bandwidth that guarantees > > > + * non-convergance. > > > + */ > > > + migrate_ensure_non_converge(from); > > > + } else { > > > + /* > > > + * Testing non-live migration, we allow it to run at > > > + * full speed to ensure short test case duration. > > > + * For tests expected to fail, we don't need to > > > + * change anything. > > > + */ > > > + if (args->result == MIG_TEST_SUCCEED) { > > > + qtest_qmp_assert_success(from, "{ 'execute' : 'stop'}"); > > > + if (!got_stop) { > > > + qtest_qmp_eventwait(from, "STOP"); > > > + } > > > + migrate_ensure_converge(from); > > > + } > > > + } > > > + > > > if (!args->connect_uri) { > > > g_autofree char *local_connect_uri = > > > migrate_get_socket_address(to, "socket-address"); > > > @@ -1352,19 +1378,29 @@ static void test_precopy_common(MigrateCommon *args) > > > qtest_set_expected_status(to, EXIT_FAILURE); > > > } > > > } else { > > > - wait_for_migration_pass(from); > > > + if (args->live) { > > > + wait_for_migration_pass(from); > > > > > > - migrate_ensure_converge(from); > > > + migrate_ensure_converge(from); > > > > > > - /* We do this first, as it has a timeout to stop us > > > - * hanging forever if migration didn't converge */ > > > - wait_for_migration_complete(from); > > > + /* > > > + * We do this first, as it has a timeout to stop us > > > + * hanging forever if migration didn't converge > > > + */ > > > + wait_for_migration_complete(from); > > > + > > > + if (!got_stop) { > > > + qtest_qmp_eventwait(from, "STOP"); > > > + } > > > + } else { > > > + wait_for_migration_complete(from); > > > > > > - if (!got_stop) { > > > - qtest_qmp_eventwait(from, "STOP"); > > > + qtest_qmp_assert_success(to, "{ 'execute' : 'cont'}"); > > > > I retested and the problem still persists. The issue is with this wait + > > cont sequence: > > > > wait_for_migration_complete(from); > > qtest_qmp_assert_success(to, "{ 'execute' : 'cont'}"); > > > > We wait for the source to finish but by the time qmp_cont executes, the > > dst is still INMIGRATE, autostart gets set and I never see the RESUME > > event. > > This is ultimately caused by the broken logic in the previous > patch 3 that looked for RESUME. The loooking for the STOP would > discard all non-STOP events, which includes the RESUME event > we were just about to look for. I've had to completely change > the event handling in migration-helpers and libqtest to fix this. Actually, no it is not. The broken logic wouldn't help, but the root cause was indeed a race condition that Fabiano points out. We are issuing the 'cont' before tgt QEMU has finished reading data from the source. The solution is actually quite simple - we must call 'query-migrate' on dst to check its status. ie the code needs to be: wait_for_migration_complete(from); wait_for_migration_complete(to); qtest_qmp_assert_success(to, "{ 'execute' : 'cont'}"); this matches what libvirt does, and libvirt has a comment saying it was not permitted to issue 'cont' before 'query-migrate' on the dst indicated completion. With 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 :|