From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51847) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1elGd3-00022G-C2 for qemu-devel@nongnu.org; Mon, 12 Feb 2018 11:06:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1elGcy-0005eQ-Um for qemu-devel@nongnu.org; Mon, 12 Feb 2018 11:06:53 -0500 Date: Mon, 12 Feb 2018 17:06:37 +0100 From: Cornelia Huck Message-ID: <20180212170637.3cdc5623.cohuck@redhat.com> In-Reply-To: <1518437672-7724-3-git-send-email-mihajlov@linux.vnet.ibm.com> References: <1518437672-7724-1-git-send-email-mihajlov@linux.vnet.ibm.com> <1518437672-7724-3-git-send-email-mihajlov@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/3] qmp: add query-cpus-fast List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Viktor Mihajlovski Cc: qemu-devel@nongnu.org, qemu-s390x@nongnu.org, lcapitulino@redhat.com, ehabkost@redhat.com, pbonzini@redhat.com, crosthwaite.peter@gmail.com, dgilbert@redhat.com, rth@twiddle.net, borntraeger@de.ibm.com, agraf@suse.de, david@redhat.com, eblake@redhat.com, armbru@redhat.com, berrange@redhat.com On Mon, 12 Feb 2018 13:14:31 +0100 Viktor Mihajlovski wrote: > From: Luiz Capitulino > > The query-cpus command has an extremely serious side effect: > it always interrupts all running vCPUs so that they can run > ioctl calls. This can cause a huge performance degradation for > some workloads. And most of the information retrieved by the > ioctl calls are not even used by query-cpus. > > This commit introduces a replacement for query-cpus called > query-cpus-fast, which has the following features: > > o Never interrupt vCPUs threads. query-cpus-fast only returns > vCPU information maintained by QEMU itself, which should be > sufficient for most management software needs > > o Make "halted" field optional: we only return it if the > halted state is maintained by QEMU. But this also gives > the option of dropping the field in the future (see below) > > o Drop irrelevant fields such as "current", "pc" and "arch" > > o Drop field "halted" since it can't be provided fast reliably > and is too volatile on most architectures to be really useful > > o Rename some fields for better clarification & proper naming > standard > > Signed-off-by: Luiz Capitulino > Signed-off-by: Viktor Mihajlovski > --- > cpus.c | 38 ++++++++++++++++++++++++++++ > hmp-commands-info.hx | 14 +++++++++++ > hmp.c | 21 ++++++++++++++++ > hmp.h | 1 + > qapi-schema.json | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 144 insertions(+) Reviewed-by: Cornelia Huck