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From: Eduardo Habkost <ehabkost@redhat.com>
To: Luiz Capitulino <lcapitulino@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>,
	"Viktor Mihajlovski" <mihajlov@linux.vnet.ibm.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	kvm@vger.kernel.org, pbonzini@redhat.com,
	"Peter Krempa" <pkrempa@redhat.com>,
	"John Ferlan" <jferlan@redhat.com>,
	libvir-list@redhat.com,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	qemu-devel@nongnu.org, "Markus Armbruster" <armbru@redhat.com>,
	"Eric Blake" <eblake@redhat.com>
Subject: Re: [RFC] kvm: x86: export vCPU halted state to sysfs
Date: Fri, 2 Feb 2018 12:50:14 -0200	[thread overview]
Message-ID: <20180202145014.GI26425@localhost.localdomain> (raw)
In-Reply-To: <20180202092159.48d9bd4c@redhat.com>

(CCing qemu-devel)

On Fri, Feb 02, 2018 at 09:21:59AM -0500, Luiz Capitulino wrote:
> On Fri, 2 Feb 2018 14:19:38 +0000
> Daniel P. Berrangé <berrange@redhat.com> wrote:
> > On Fri, Feb 02, 2018 at 12:15:54PM -0200, Eduardo Habkost wrote:
[...]
> > > It would be also interesting to update QEMU QMP documentation to
> > > clarify the arch-specific semantics of "halted".  
> > 
> > Any also especially clarify the awful performance implications of running
> > this particular query command. In general I would not expect query-xxx
> > monitor commands to interrupt all vcpus, so we should clearly warn about
> > this !
> 
> Or deprecate it...

We could deprecate the expensive fields on query-cpus, and move
them to a more expensive query-cpu-state command.  I believe most
users of query-cpus are only interested in qom_path, thread_id,
and topology info.

Markus, Eric: from the QAPI point of view, is it OK to remove
fields between QEMU versions, as long as we follow our
deprecation policy?

-- 
Eduardo

WARNING: multiple messages have this Message-ID (diff)
From: Eduardo Habkost <ehabkost@redhat.com>
To: Luiz Capitulino <lcapitulino@redhat.com>
Cc: "Daniel P. Berrangé" <berrange@redhat.com>,
	"Viktor Mihajlovski" <mihajlov@linux.vnet.ibm.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	kvm@vger.kernel.org, pbonzini@redhat.com,
	"Peter Krempa" <pkrempa@redhat.com>,
	"John Ferlan" <jferlan@redhat.com>,
	libvir-list@redhat.com,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	qemu-devel@nongnu.org, "Markus Armbruster" <armbru@redhat.com>,
	"Eric Blake" <eblake@redhat.com>
Subject: Re: [Qemu-devel] [RFC] kvm: x86: export vCPU halted state to sysfs
Date: Fri, 2 Feb 2018 12:50:14 -0200	[thread overview]
Message-ID: <20180202145014.GI26425@localhost.localdomain> (raw)
In-Reply-To: <20180202092159.48d9bd4c@redhat.com>

(CCing qemu-devel)

On Fri, Feb 02, 2018 at 09:21:59AM -0500, Luiz Capitulino wrote:
> On Fri, 2 Feb 2018 14:19:38 +0000
> Daniel P. Berrangé <berrange@redhat.com> wrote:
> > On Fri, Feb 02, 2018 at 12:15:54PM -0200, Eduardo Habkost wrote:
[...]
> > > It would be also interesting to update QEMU QMP documentation to
> > > clarify the arch-specific semantics of "halted".  
> > 
> > Any also especially clarify the awful performance implications of running
> > this particular query command. In general I would not expect query-xxx
> > monitor commands to interrupt all vcpus, so we should clearly warn about
> > this !
> 
> Or deprecate it...

We could deprecate the expensive fields on query-cpus, and move
them to a more expensive query-cpu-state command.  I believe most
users of query-cpus are only interested in qom_path, thread_id,
and topology info.

Markus, Eric: from the QAPI point of view, is it OK to remove
fields between QEMU versions, as long as we follow our
deprecation policy?

-- 
Eduardo

  reply	other threads:[~2018-02-02 14:50 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-01 17:54 [RFC] kvm: x86: export vCPU halted state to sysfs Luiz Capitulino
2018-02-01 20:15 ` Radim Krčmář
2018-02-01 20:26   ` Eduardo Habkost
2018-02-02 13:53     ` Viktor Mihajlovski
2018-02-02 14:14       ` Luiz Capitulino
2018-02-02 14:15       ` Eduardo Habkost
2018-02-02 14:19         ` Daniel P. Berrangé
2018-02-02 14:21           ` Luiz Capitulino
2018-02-02 14:50             ` Eduardo Habkost [this message]
2018-02-02 14:50               ` [Qemu-devel] " Eduardo Habkost
2018-02-02 14:55               ` [libvirt] " Luiz Capitulino
2018-02-02 14:55                 ` [Qemu-devel] " Luiz Capitulino
2018-02-02 15:07               ` Daniel P. Berrangé
2018-02-02 15:07                 ` [Qemu-devel] " Daniel P. Berrangé
2018-02-02 15:25                 ` Eduardo Habkost
2018-02-02 15:25                   ` [Qemu-devel] " Eduardo Habkost
2018-02-02 16:23                   ` [libvirt] " Eric Blake
2018-02-02 16:23                     ` [Qemu-devel] " Eric Blake
2018-02-02 15:19               ` [libvirt] " Eric Blake
2018-02-02 15:19                 ` [Qemu-devel] " Eric Blake
2018-02-02 17:23               ` Dr. David Alan Gilbert
2018-02-02 17:38                 ` Eduardo Habkost
2018-02-02 15:08         ` Viktor Mihajlovski
2018-02-02 15:22           ` [libvirt] " Luiz Capitulino
2018-02-02 15:51             ` Viktor Mihajlovski
2018-02-02 15:54               ` Daniel P. Berrangé
2018-02-02 16:01                 ` Luiz Capitulino
2018-02-02 16:07                   ` Luiz Capitulino
2018-02-02 16:19                   ` Viktor Mihajlovski
2018-02-02 17:42                     ` [libvirt] " Eduardo Habkost
2018-02-02 18:50                       ` Luiz Capitulino
2018-02-02 20:09                         ` Eduardo Habkost
2018-02-02 20:19                           ` [libvirt] " Luiz Capitulino
2018-02-02 20:41                             ` Eduardo Habkost
2018-02-02 21:49                               ` Luiz Capitulino
2018-02-02 21:54                                 ` Luiz Capitulino
2018-02-05 13:43                               ` Viktor Mihajlovski
2018-02-05 13:47                                 ` Daniel P. Berrangé
2018-02-05 15:37                                   ` Luiz Capitulino
2018-02-05 16:10                                     ` Viktor Mihajlovski
2018-02-05 16:36                                       ` Luiz Capitulino
2018-02-05 22:50                                     ` Eduardo Habkost
2018-02-06  2:04                                       ` Luiz Capitulino
2018-02-02 15:55               ` [libvirt] " Luiz Capitulino
2018-02-06 10:29     ` Viktor Mihajlovski
2018-02-06 14:05       ` Luiz Capitulino
2018-02-02 12:47   ` Daniel P. Berrangé
2018-02-02 13:46     ` Luiz Capitulino
2018-02-02 12:49 ` Daniel P. Berrangé
2018-02-02 13:49   ` Luiz Capitulino

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