From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Habkost Subject: Re: [RFC] kvm: x86: export vCPU halted state to sysfs Date: Fri, 2 Feb 2018 12:50:14 -0200 Message-ID: <20180202145014.GI26425@localhost.localdomain> References: <20180201125441.2f5b4fdd@redhat.com> <20180201201514.GB660@flask> <20180201202649.GG26425@localhost.localdomain> <20180202141554.GH26425@localhost.localdomain> <20180202141938.GJ15403@redhat.com> <20180202092159.48d9bd4c@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Viktor Mihajlovski , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, pbonzini@redhat.com, Peter Krempa , John Ferlan , libvir-list@redhat.com, Christian Borntraeger , qemu-devel@nongnu.org, Markus Armbruster , Eric Blake To: Luiz Capitulino Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53898 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751887AbeBBOuU (ORCPT ); Fri, 2 Feb 2018 09:50:20 -0500 Content-Disposition: inline In-Reply-To: <20180202092159.48d9bd4c@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: (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 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45290) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ehcfd-0006OJ-D0 for qemu-devel@nongnu.org; Fri, 02 Feb 2018 09:50:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ehcfW-0006mt-Qe for qemu-devel@nongnu.org; Fri, 02 Feb 2018 09:50:28 -0500 Received: from mx1.redhat.com ([209.132.183.28]:40602) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ehcfW-0006kx-90 for qemu-devel@nongnu.org; Fri, 02 Feb 2018 09:50:22 -0500 Date: Fri, 2 Feb 2018 12:50:14 -0200 From: Eduardo Habkost Message-ID: <20180202145014.GI26425@localhost.localdomain> References: <20180201125441.2f5b4fdd@redhat.com> <20180201201514.GB660@flask> <20180201202649.GG26425@localhost.localdomain> <20180202141554.GH26425@localhost.localdomain> <20180202141938.GJ15403@redhat.com> <20180202092159.48d9bd4c@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20180202092159.48d9bd4c@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC] kvm: x86: export vCPU halted state to sysfs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luiz Capitulino Cc: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= , Viktor Mihajlovski , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, pbonzini@redhat.com, Peter Krempa , John Ferlan , libvir-list@redhat.com, Christian Borntraeger , qemu-devel@nongnu.org, Markus Armbruster , Eric Blake (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. Berrang=E9 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". =20 > >=20 > > Any also especially clarify the awful performance implications of run= ning > > this particular query command. In general I would not expect query-xx= x > > monitor commands to interrupt all vcpus, so we should clearly warn ab= out > > this ! >=20 > 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? --=20 Eduardo