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 302CEC433F5 for ; Fri, 3 Dec 2021 14:02:32 +0000 (UTC) Received: from localhost ([::1]:34410 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mt98w-0006Wp-RO for qemu-devel@archiver.kernel.org; Fri, 03 Dec 2021 09:02:30 -0500 Received: from eggs.gnu.org ([209.51.188.92]:42658) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mt97a-0005Rb-Tn for qemu-devel@nongnu.org; Fri, 03 Dec 2021 09:01:07 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24848) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mt97O-0008LO-L2 for qemu-devel@nongnu.org; Fri, 03 Dec 2021 09:01:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638540051; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UzwGy81mfESFphtsbFQRCeApxdrL0bc7YWnd+1fQnHE=; b=Vqx7Q+N1/91hpfg6N78JphJK253sBOmravyXvA7z/VPZoV5S9lsDSeweBMldKLfDM2vVf4 oBlyqakRN7R0fmD28LABpOan0YfUdr0zfrWyARcs9JRMd33UTFO/tmKxeaEO0ZG2Ey1cJe 3kJqjvMZ2v8i4CWMBuI0O9x2yzzwqRU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-272-kM-3ZePZOGWz6ggIztc3mw-1; Fri, 03 Dec 2021 09:00:46 -0500 X-MC-Unique: kM-3ZePZOGWz6ggIztc3mw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EE0083DD24; Fri, 3 Dec 2021 14:00:45 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.127]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7A7E25F4E0; Fri, 3 Dec 2021 14:00:41 +0000 (UTC) Date: Fri, 3 Dec 2021 14:00:39 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Li Zhang Subject: Re: [PATCH v2 1/1] multifd: Shut down the QIO channels to avoid blocking the send threads when they are terminated. Message-ID: References: <20211203115533.31534-1-lizhang@suse.de> <20211203115533.31534-2-lizhang@suse.de> MIME-Version: 1.0 In-Reply-To: <20211203115533.31534-2-lizhang@suse.de> User-Agent: Mutt/2.1.3 (2021-09-10) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 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 Content-Transfer-Encoding: 8bit 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: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.717, 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_H2=-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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: qemu-devel@nongnu.org, cfontana@suse.de, dgilbert@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Dec 03, 2021 at 12:55:33PM +0100, Li Zhang wrote: > When doing live migration with multifd channels 8, 16 or larger number, > the guest hangs in the presence of the network errors such as missing TCP ACKs. > > At sender's side: > The main thread is blocked on qemu_thread_join, migration_fd_cleanup > is called because one thread fails on qio_channel_write_all when > the network problem happens and other send threads are blocked on sendmsg. > They could not be terminated. So the main thread is blocked on qemu_thread_join > to wait for the threads terminated. > > (gdb) bt > 0 0x00007f30c8dcffc0 in __pthread_clockjoin_ex () at /lib64/libpthread.so.0 > 1 0x000055cbb716084b in qemu_thread_join (thread=0x55cbb881f418) at ../util/qemu-thread-posix.c:627 > 2 0x000055cbb6b54e40 in multifd_save_cleanup () at ../migration/multifd.c:542 > 3 0x000055cbb6b4de06 in migrate_fd_cleanup (s=0x55cbb8024000) at ../migration/migration.c:1808 > 4 0x000055cbb6b4dfb4 in migrate_fd_cleanup_bh (opaque=0x55cbb8024000) at ../migration/migration.c:1850 > 5 0x000055cbb7173ac1 in aio_bh_call (bh=0x55cbb7eb98e0) at ../util/async.c:141 > 6 0x000055cbb7173bcb in aio_bh_poll (ctx=0x55cbb7ebba80) at ../util/async.c:169 > 7 0x000055cbb715ba4b in aio_dispatch (ctx=0x55cbb7ebba80) at ../util/aio-posix.c:381 > 8 0x000055cbb7173ffe in aio_ctx_dispatch (source=0x55cbb7ebba80, callback=0x0, user_data=0x0) at ../util/async.c:311 > 9 0x00007f30c9c8cdf4 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0 > 10 0x000055cbb71851a2 in glib_pollfds_poll () at ../util/main-loop.c:232 > 11 0x000055cbb718521c in os_host_main_loop_wait (timeout=42251070366) at ../util/main-loop.c:255 > 12 0x000055cbb7185321 in main_loop_wait (nonblocking=0) at ../util/main-loop.c:531 > 13 0x000055cbb6e6ba27 in qemu_main_loop () at ../softmmu/runstate.c:726 > 14 0x000055cbb6ad6fd7 in main (argc=68, argv=0x7ffc0c578888, envp=0x7ffc0c578ab0) at ../softmmu/main.c:50 > > To make sure that the send threads could be terminated, IO channels should be > shut down to avoid waiting IO. > > Signed-off-by: Li Zhang > --- > migration/multifd.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/migration/multifd.c b/migration/multifd.c > index 7c9deb1921..33f8287969 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -523,6 +523,9 @@ static void multifd_send_terminate_threads(Error *err) > qemu_mutex_lock(&p->mutex); > p->quit = true; > qemu_sem_post(&p->sem); > + if (p->c) { > + qio_channel_shutdown(p->c, QIO_CHANNEL_SHUTDOWN_BOTH, NULL); > + } > qemu_mutex_unlock(&p->mutex); > } > } Reviewed-by: Daniel P. Berrangé 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 :|