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 lists1p.gnu.org (lists1p.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 DC72AC5DF82 for ; Thu, 20 Aug 2026 08:18:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wwxyD-0004iF-DB; Thu, 20 Aug 2026 04:17:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wwxyB-0004hM-O7 for qemu-devel@nongnu.org; Thu, 20 Aug 2026 04:17:51 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wwxy9-0003Jh-O4 for qemu-devel@nongnu.org; Thu, 20 Aug 2026 04:17:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1787213867; 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=GZkCWkJjYtaXDgztuqt6I73F66TW18sXpLStFtvAJjo=; b=ZZKjoqAoBhctmnHrzlkr7KrkgRD1YMcXetrQwnrgZtRKxClfrNLU+ycv7SDv4xdpRLg/5d otCxUmW0X9uGCe/N+5/M+bnyOkcfBYkWZKNJdj+KC2troRj7NFLQt1I4mNcabo559ZYI+U WYaori51v9sXRMEkYl7nKm2gER/6pok= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-665-82tYoyvVNf-JMEY_bBcSHg-1; Thu, 20 Aug 2026 04:17:43 -0400 X-MC-Unique: 82tYoyvVNf-JMEY_bBcSHg-1 X-Mimecast-MFC-AGG-ID: 82tYoyvVNf-JMEY_bBcSHg_1787213863 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D903B19560AA; Thu, 20 Aug 2026 08:17:42 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.12]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6013219560AB; Thu, 20 Aug 2026 08:17:42 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id E852121E6920; Thu, 20 Aug 2026 10:17:39 +0200 (CEST) From: Markus Armbruster To: Zhang Chen Cc: qemu-devel , Eric Blake , "'Michael S . Tsirkin'" , Stefan Hajnoczi , Paolo Bonzini , 'Daniel P . =?utf-8?Q?Berrang=C3=A9'?= , Jason Wang Subject: Re: [PATCH V12 13/15] monitor/hmp: display IOThread holders In-Reply-To: <20260814174830.1691540-14-zhangckid@gmail.com> (Zhang Chen's message of "Sat, 15 Aug 2026 01:48:27 +0800") References: <20260814174830.1691540-1-zhangckid@gmail.com> <20260814174830.1691540-14-zhangckid@gmail.com> Date: Thu, 20 Aug 2026 10:17:39 +0200 Message-ID: <87y0e12okc.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 9 X-Spam_score: 0.9 X-Spam_bar: / X-Spam_report: (0.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.341, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Zhang Chen writes: > Display holder information in info iothreads to aid manual debugging. > Omit the holders line when an IOThread has no holders. > > Signed-off-by: Zhang Chen > --- > monitor/hmp-cmds.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c > index e9fb8d827a..41a813e79f 100644 > --- a/monitor/hmp-cmds.c > +++ b/monitor/hmp-cmds.c > @@ -240,11 +240,32 @@ void hmp_info_iothreads(Monitor *mon, const QDict *qdict) > IOThreadInfoList *info_list = qmp_query_iothreads(NULL); > IOThreadInfoList *info; > IOThreadInfo *value; > + IOThreadHolderList *h; > > for (info = info_list; info; info = info->next) { > value = info->value; > monitor_printf(mon, "%s:\n", value->id); > monitor_printf(mon, " thread_id=%" PRId64 "\n", value->thread_id); > + monitor_printf(mon, " holders="); > + for (h = value->holders; h; h = h->next) { > + IOThreadHolder *holder = h->value; > + > + switch (holder->type) { > + case IO_THREAD_HOLDER_KIND_BLOCK_EXPORT: > + monitor_printf(mon, "[block-export: %s]", > + holder->u.block_export.export_id); > + break; > + case IO_THREAD_HOLDER_KIND_QOM_OBJECT: > + monitor_printf(mon, "[qom-path: %s]", > + holder->u.qom_object.qom_path); > + break; > + default: > + monitor_printf(mon, "[unknown]"); > + break; This is unreachable. Please use default: g_assert_not_reached(); to make it obvious. > + } > + } > + monitor_printf(mon, "\n"); > + > monitor_printf(mon, " poll-max-ns=%" PRId64 "\n", value->poll_max_ns); > monitor_printf(mon, " poll-grow=%" PRId64 "\n", value->poll_grow); > monitor_printf(mon, " poll-shrink=%" PRId64 "\n", value->poll_shrink); Quick test: $ qemu-system-x86_64 -S -nodefaults -display none -chardev socket,id=chr-qmp,path=test-qmp,server=on,wait=off -object monitor-qmp,id=qmp,chardev=chr-qmp -monitor stdio QEMU 11.1.50 monitor - type 'help' for more information (qemu) info iothreads (qemu) q Hmm, no output? The QMP monitor should be holding the monitor I/O thread. To confirm that, I made monitor_complete() print things (patch appended), and got ### monitor qmp holding iothread mon_iothread ### monitor compat_monitor0 without iothread What's going on here? diff --git a/monitor/monitor.c b/monitor/monitor.c index 26e7ef4d35..57672dbe0e 100644 --- a/monitor/monitor.c +++ b/monitor/monitor.c @@ -751,8 +751,13 @@ static void monitor_complete(UserCreatable *uc, Error **errp) }; mon->ctx = iothread_ref_and_get_aio_context(mon_iothread, &io_holder); + printf("### monitor %s holding iothread %s\n", + object_get_canonical_path_component(OBJECT(mon)), + iothread_get_id(mon_iothread)); } else { mon->ctx = qemu_get_aio_context(); + printf("### monitor %s without iothread\n", + object_get_canonical_path_component(OBJECT(mon))); } mon->accept_input_bh = aio_bh_new(mon->ctx, monitor_accept_input, mon); }