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 03239E63F2B for ; Tue, 17 Feb 2026 07:51:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vsFrb-0000SS-PC; Tue, 17 Feb 2026 02:51:19 -0500 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 1vsFrX-0000SG-UZ for qemu-devel@nongnu.org; Tue, 17 Feb 2026 02:51:16 -0500 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 1vsFrW-0003KX-9k for qemu-devel@nongnu.org; Tue, 17 Feb 2026 02:51:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1771314672; 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=Phars+mJG5yKR/1oErrVSZdj1G7B6wUb3lqEpzYli/A=; b=VILAWZSzzc/ELE1FkZ9kMKuxIb1pkuccihQZPzE5ry/Eg1mndT/uYAW1ujgQE5XXJNVw8E pB+JlymQuGcW7iG+joaczs6O7IaPRq8r7mnhmhmMVPWfjGhYXv10kv82aUMltXoChx2sLC 7OnGCG6g6B4kw46+RDF2XJwX0yKXguU= Received: from mx-prod-mc-03.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-161-2CD2rHs9M3qzZrSsHMpxaA-1; Tue, 17 Feb 2026 02:51:08 -0500 X-MC-Unique: 2CD2rHs9M3qzZrSsHMpxaA-1 X-Mimecast-MFC-AGG-ID: 2CD2rHs9M3qzZrSsHMpxaA_1771314667 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7EC7E1956052; Tue, 17 Feb 2026 07:51:07 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.14]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B26BF1800348; Tue, 17 Feb 2026 07:51:06 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 3A00021E692D; Tue, 17 Feb 2026 08:51:04 +0100 (CET) From: Markus Armbruster To: Zhang Chen Cc: qemu-devel , "Dr . David Alan Gilbert" , Eric Blake , "Michael S . Tsirkin" , Stefan Hajnoczi Subject: Re: [PATCH V4 4/4] qapi: examine IOThread attachment status via query-iothreads In-Reply-To: <20260213171622.55629-4-zhangckid@gmail.com> (Zhang Chen's message of "Sat, 14 Feb 2026 01:16:22 +0800") References: <20260213171622.55629-1-zhangckid@gmail.com> <20260213171622.55629-4-zhangckid@gmail.com> Date: Tue, 17 Feb 2026 08:51:04 +0100 Message-ID: <87wm0bq047.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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: -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, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-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: 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: > Extend the 'IOThreadInfo' structure to include attachment metrics. > This allows users to monitor how many devices are associated with > a specific IOThread and identify them by their QOM paths. > > New fields added to IOThreadInfo: > - @attached-cnt: An integer representing the number of devices > currently using this IOThread's AioContext. > - @attached-dev: A string containing a delimited list ("|") of > QOM paths for the attached devices. > > These fields are also exposed via the Human Monitor Interface (HMP) > command 'info iothreads' to assist with manual debugging and > performance tuning. > > Example QMP output: > { > "id": "iothread0", > "thread-id": 3134, > "attached-cnt": 2, > "attached-dev": "/machine/peripheral/blk1/virtio-backend | /machine/peripheral/blk0/virtio-backend", > ... > } > > Signed-off-by: Zhang Chen [...] > diff --git a/qapi/misc.json b/qapi/misc.json > index 1f5062df2a..ca53638684 100644 > --- a/qapi/misc.json > +++ b/qapi/misc.json > @@ -76,6 +76,19 @@ > # > # @thread-id: ID of the underlying host thread > # > +# @attached-cnt: The parameter is a counter indicating how many > +# active devices are currently associated with this iothread > +# (e.g. virtio-blk). In hotplug scenarios, users can > +# pre-allocate multiple iothread objects to serve as a persistent > +# thread pool. When a device is hot-unplugged, the corresponding > +# IOThread is released but remains available, allowing subsequent > +# hot-plugged devices to attach to and reuse the existing thread. > +# (since 11.0) > +# > +# @attached-dev: A list of QOM paths for the devices currently > +# associated with this IOThread, delimited by " | ". > +# Returns "none" if no devices are attached. (since 11.0) QAPI schema design maxim: do not encode structured data as strings. @attached-devs should be an array of QOM paths instead. Unless I misunderstand your docs, @attached-cnt is the number of QOM paths in @attached-dev, i.e. @attached-dev is redundant. If this is the case, drop it. If it isn't, educate me :) We generally avoid abbreviations in the QAPI schema: @attached-count, @attached-devices. > +# > # @poll-max-ns: maximum polling time in ns, 0 means polling is > # disabled (since 2.9) > # > @@ -93,6 +106,8 @@ > { 'struct': 'IOThreadInfo', > 'data': {'id': 'str', > 'thread-id': 'int', > + 'attached-cnt': 'int', > + 'attached-dev': 'str', > 'poll-max-ns': 'int', > 'poll-grow': 'int', > 'poll-shrink': 'int', > @@ -118,6 +133,8 @@ > # { > # "id":"iothread0", > # "thread-id":3134, > +# "attached-cnt":2, > +# "attached-dev":/machine/peripheral/blk1/virtio-backend | /machine/peripheral/blk0/virtio-backend, Once again, the example is syntactically incorrect (the value lacks double quotes), and once again I recommend to create example I/O by actually running a test. Getting tired of this, to be frank. > # "poll-max-ns":32768, > # "poll-grow":0, > # "poll-shrink":0, > @@ -126,6 +143,8 @@ > # { > # "id":"iothread1", > # "thread-id":3135, > +# "attached-cnt":1, > +# "attached-dev":/machine/peripheral/blk3/virtio-backend, Likewise. > # "poll-max-ns":32768, > # "poll-grow":0, > # "poll-shrink":0,