From nobody Wed Oct 22 12:50:04 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1519738537606592.1764293757727; Tue, 27 Feb 2018 05:35:37 -0800 (PST) Received: from localhost ([::1]:37142 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eqfPs-0008Aq-Af for importer@patchew.org; Tue, 27 Feb 2018 08:35:36 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35046) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eqfDo-0005yO-Of for qemu-devel@nongnu.org; Tue, 27 Feb 2018 08:23:10 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eqfDn-0000EO-96 for qemu-devel@nongnu.org; Tue, 27 Feb 2018 08:23:08 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51880 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eqfDn-0000E9-3x; Tue, 27 Feb 2018 08:23:07 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id ADC2E40201A5; Tue, 27 Feb 2018 13:23:06 +0000 (UTC) Received: from localhost (ovpn-117-77.ams2.redhat.com [10.36.117.77]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 551372024CA2; Tue, 27 Feb 2018 13:23:04 +0000 (UTC) From: Cornelia Huck To: peter.maydell@linaro.org Date: Tue, 27 Feb 2018 14:21:44 +0100 Message-Id: <20180227132150.13847-21-cohuck@redhat.com> In-Reply-To: <20180227132150.13847-1-cohuck@redhat.com> References: <20180227132150.13847-1-cohuck@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Tue, 27 Feb 2018 13:23:06 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Tue, 27 Feb 2018 13:23:06 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'cohuck@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PULL 20/26] qmp: add query-cpus-fast X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thuth@redhat.com, david@redhat.com, Viktor Mihajlovski , Cornelia Huck , qemu-devel@nongnu.org, agraf@suse.de, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, Luiz Capitulino , rth@twiddle.net Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 Drop "halted" field as it can not be retrieved in a fast way on most architectures o Drop irrelevant fields such as "current", "pc" and "arch" o Rename some fields for better clarification & proper naming standard Signed-off-by: Luiz Capitulino Signed-off-by: Viktor Mihajlovski Message-Id: <1518797321-28356-3-git-send-email-mihajlov@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck Reviewed-by: Eric Blake Signed-off-by: Cornelia Huck --- cpus.c | 38 ++++++++++++++++++++++++++++++ qapi-schema.json | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++= ++++ 2 files changed, 108 insertions(+) diff --git a/cpus.c b/cpus.c index 6006931d3a..6df6660ccf 100644 --- a/cpus.c +++ b/cpus.c @@ -2156,6 +2156,44 @@ CpuInfoList *qmp_query_cpus(Error **errp) return head; } =20 +/* + * fast means: we NEVER interrupt vCPU threads to retrieve + * information from KVM. + */ +CpuInfoFastList *qmp_query_cpus_fast(Error **errp) +{ + MachineState *ms =3D MACHINE(qdev_get_machine()); + MachineClass *mc =3D MACHINE_GET_CLASS(ms); + CpuInfoFastList *head =3D NULL, *cur_item =3D NULL; + CPUState *cpu; + + CPU_FOREACH(cpu) { + CpuInfoFastList *info =3D g_malloc0(sizeof(*info)); + info->value =3D g_malloc0(sizeof(*info->value)); + + info->value->cpu_index =3D cpu->cpu_index; + info->value->qom_path =3D object_get_canonical_path(OBJECT(cpu)); + info->value->thread_id =3D cpu->thread_id; + + info->value->has_props =3D !!mc->cpu_index_to_instance_props; + if (info->value->has_props) { + CpuInstanceProperties *props; + props =3D g_malloc0(sizeof(*props)); + *props =3D mc->cpu_index_to_instance_props(ms, cpu->cpu_index); + info->value->props =3D props; + } + + if (!cur_item) { + head =3D cur_item =3D info; + } else { + cur_item->next =3D info; + cur_item =3D info; + } + } + + return head; +} + void qmp_memsave(int64_t addr, int64_t size, const char *filename, bool has_cpu, int64_t cpu_index, Error **errp) { diff --git a/qapi-schema.json b/qapi-schema.json index 94d560ed13..815f072876 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -552,6 +552,12 @@ # # Returns a list of information about each virtual CPU. # +# This command causes vCPU threads to exit to userspace, which causes +# a small interruption to guest CPU execution. This will have a negative +# impact on realtime guests and other latency sensitive guest workloads. +# It is recommended to use @query-cpus-fast instead of this command to +# avoid the vCPU interruption. +# # Returns: a list of @CpuInfo for each virtual CPU # # Since: 0.14.0 @@ -585,6 +591,70 @@ { 'command': 'query-cpus', 'returns': ['CpuInfo'] } =20 ## +# @CpuInfoFast: +# +# Information about a virtual CPU +# +# @cpu-index: index of the virtual CPU +# +# @qom-path: path to the CPU object in the QOM tree +# +# @thread-id: ID of the underlying host thread +# +# @props: properties describing to which node/socket/core/thread +# virtual CPU belongs to, provided if supported by board +# +# Since: 2.12 +# +## +{ 'struct': 'CpuInfoFast', + 'data': {'cpu-index': 'int', 'qom-path': 'str', + 'thread-id': 'int', '*props': 'CpuInstanceProperties' } } + +## +# @query-cpus-fast: +# +# Returns information about all virtual CPUs. This command does not +# incur a performance penalty and should be used in production +# instead of query-cpus. +# +# Returns: list of @CpuInfoFast +# +# Notes: The CPU architecture name is not returned by query-cpus-fast. +# Use query-target to retrieve that information. +# +# Since: 2.12 +# +# Example: +# +# -> { "execute": "query-cpus-fast" } +# <- { "return": [ +# { +# "thread-id": 25627, +# "props": { +# "core-id": 0, +# "thread-id": 0, +# "socket-id": 0 +# }, +# "qom-path": "/machine/unattached/device[0]", +# "cpu-index": 0 +# }, +# { +# "thread-id": 25628, +# "props": { +# "core-id": 0, +# "thread-id": 0, +# "socket-id": 1 +# }, +# "qom-path": "/machine/unattached/device[2]", +# "cpu-index": 1 +# } +# ] +# } +## +{ 'command': 'query-cpus-fast', 'returns': [ 'CpuInfoFast' ] } + +## # @IOThreadInfo: # # Information about an iothread --=20 2.13.6