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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B58F0C54EBD for ; Thu, 12 Jan 2023 12:14:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230027AbjALMOD (ORCPT ); Thu, 12 Jan 2023 07:14:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235311AbjALMNh (ORCPT ); Thu, 12 Jan 2023 07:13:37 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA7A0CFF for ; Thu, 12 Jan 2023 04:10:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673525431; 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:in-reply-to:in-reply-to: references:references; bh=m7ctaQSqwJCI8HWipVGgCP7kRuDp6u50d7Qpz/siyqg=; b=boYypGOIer8qnRi+GRIu8AkzfJuZBhyI9ghZkP/36s9AxEwJwldCiTcSNso17lGpenySgG 9FNNx1/x2HPeTVOaZhE1EGDgzKwyNrcbvDq3R4YkyrwaI1c7Kkb6F+2gzQB0Ys4/7+86b+ sK/UT5IvW86ohYT6ic92lYuSE8x/+9E= 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-655-6czC9ptYO4qvkpmqbRPPwg-1; Thu, 12 Jan 2023 07:10:28 -0500 X-MC-Unique: 6czC9ptYO4qvkpmqbRPPwg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2D3C4802C1C; Thu, 12 Jan 2023 12:10:27 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.222]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AC12E140EBF5; Thu, 12 Jan 2023 12:10:24 +0000 (UTC) Date: Thu, 12 Jan 2023 12:10:22 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Pierre Morel Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, borntraeger@de.ibm.com, pasic@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, thuth@redhat.com, cohuck@redhat.com, mst@redhat.com, pbonzini@redhat.com, kvm@vger.kernel.org, ehabkost@redhat.com, marcel.apfelbaum@gmail.com, eblake@redhat.com, armbru@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com, scgl@linux.ibm.com, frankja@linux.ibm.com, clg@kaod.org Subject: Re: [PATCH v14 09/11] qapi/s390/cpu topology: monitor query topology information Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20230105145313.168489-1-pmorel@linux.ibm.com> <20230105145313.168489-10-pmorel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230105145313.168489-10-pmorel@linux.ibm.com> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jan 05, 2023 at 03:53:11PM +0100, Pierre Morel wrote: > Reporting the current topology informations to the admin through > the QEMU monitor. > > Signed-off-by: Pierre Morel > --- > qapi/machine-target.json | 66 ++++++++++++++++++++++++++++++++++ > include/monitor/hmp.h | 1 + > hw/s390x/cpu-topology.c | 76 ++++++++++++++++++++++++++++++++++++++++ > hmp-commands-info.hx | 16 +++++++++ > 4 files changed, 159 insertions(+) > > diff --git a/qapi/machine-target.json b/qapi/machine-target.json > index 75b0aa254d..927618a78f 100644 > --- a/qapi/machine-target.json > +++ b/qapi/machine-target.json > @@ -371,3 +371,69 @@ > }, > 'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] } > } > + > +## > +# @S390CpuTopology: > +# > +# CPU Topology information > +# > +# @drawer: the destination drawer where to move the vCPU > +# > +# @book: the destination book where to move the vCPU > +# > +# @socket: the destination socket where to move the vCPU > +# > +# @polarity: optional polarity, default is last polarity set by the guest > +# > +# @dedicated: optional, if the vCPU is dedicated to a real CPU > +# > +# @origin: offset of the first bit of the core mask > +# > +# @mask: mask of the cores sharing the same topology > +# > +# Since: 8.0 > +## > +{ 'struct': 'S390CpuTopology', > + 'data': { > + 'drawer': 'int', > + 'book': 'int', > + 'socket': 'int', > + 'polarity': 'int', > + 'dedicated': 'bool', > + 'origin': 'int', > + 'mask': 'str' > + }, > + 'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] } > +} > + > +## > +# @query-topology: > +# > +# Return information about CPU Topology > +# > +# Returns a @CpuTopology instance describing the CPU Toplogy > +# being currently used by QEMU. > +# > +# Since: 8.0 > +# > +# Example: > +# > +# -> { "execute": "cpu-topology" } > +# <- {"return": [ > +# { > +# "drawer": 0, > +# "book": 0, > +# "socket": 0, > +# "polarity": 0, > +# "dedicated": true, > +# "origin": 0, > +# "mask": 0xc000000000000000, > +# }, > +# ] > +# } > +# > +## > +{ 'command': 'query-topology', > + 'returns': ['S390CpuTopology'], > + 'if': { 'all': [ 'TARGET_S390X', 'CONFIG_KVM' ] } > +} IIUC, you're using @mask as a way to compress the array returned from query-topology, so that it doesn't have any repeated elements with the same data. I guess I can understand that desire when the core count can get very large, this can have a large saving. The downside of using @mask, is that now you require the caller to parse the string to turn it into a bitmask and expand the data. Generally this is considered a bit of an anti-pattern in QAPI design - we don't want callers to have to further parse the data to extract information, we want to directly consumable from the parsed JSON doc. We already have 'query-cpus-fast' wich returns one entry for each CPU. In fact why do we need to add query-topology at all. Can't we just add book-id / drawer-id / polarity / dedicated to the query-cpus-fast result ? 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 :|