From nobody Sat Apr 27 15:35:33 2024 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 1518026035391291.00763248088526; Wed, 7 Feb 2018 09:53:55 -0800 (PST) Received: from localhost ([::1]:39405 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejTus-0007MF-Kx for importer@patchew.org; Wed, 07 Feb 2018 12:53:54 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53194) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejTrh-00056D-4T for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ejTrf-0002lk-HX for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:37 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49634 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 1ejTrf-0002lG-AM for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:35 -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 D16DA404084A; Wed, 7 Feb 2018 17:50:24 +0000 (UTC) Received: from localhost (ovpn-116-92.phx2.redhat.com [10.3.116.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id 80E582024CA5; Wed, 7 Feb 2018 17:50:24 +0000 (UTC) From: Luiz Capitulino To: qemu-devel@nongnu.org Date: Wed, 7 Feb 2018 12:50:13 -0500 Message-Id: <20180207175014.11157-2-lcapitulino@redhat.com> In-Reply-To: <20180207175014.11157-1-lcapitulino@redhat.com> References: <20180207175014.11157-1-lcapitulino@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 [10.11.55.5]); Wed, 07 Feb 2018 17:50:24 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Wed, 07 Feb 2018 17:50:24 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lcapitulino@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] [PATCH 1/2] 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: mihajlov@linux.vnet.ibm.com, armbru@redhat.com, ehabkost@redhat.com 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" The query-cpus command has an extremely serious side effect: it always interrupt 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 Rename some fields for better clarification & proper naming standard The "halted" field is somewhat controversial. On the one hand, it offers a convenient way to know if a guest CPU is idle or running. On the other hand, it's a field that can change many times a second. In fact, the halted state can change even before query-cpus-fast has returned. This makes one wonder if this field should be dropped all together. Having the "halted" field as optional gives a better option for dropping it in the future, since we can just stop returning it. Signed-off-by: Luiz Capitulino --- cpus.c | 44 ++++++++++++++++++++++++++++++++ hmp-commands-info.hx | 14 +++++++++++ hmp.c | 24 ++++++++++++++++++ hmp.h | 1 + qapi-schema.json | 71 ++++++++++++++++++++++++++++++++++++++++++++++++= ++++ 5 files changed, 154 insertions(+) diff --git a/cpus.c b/cpus.c index 2cb0af9b22..3b68a8146c 100644 --- a/cpus.c +++ b/cpus.c @@ -2083,6 +2083,50 @@ CpuInfoList *qmp_query_cpus(Error **errp) return head; } =20 +/* + * fast means: we NEVER interrupt vCPU threads to retrieve + * information from KVM. + */ +CpuInfo2List *qmp_query_cpus_fast(Error **errp) +{ + MachineState *ms =3D MACHINE(qdev_get_machine()); + MachineClass *mc =3D MACHINE_GET_CLASS(ms); + CpuInfo2List *head =3D NULL, *cur_item =3D NULL; + CPUState *cpu; + + CPU_FOREACH(cpu) { + CpuInfo2List *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 in kernel irqchip is used, we don't have 'halted' */ + info->value->has_halted =3D !kvm_irqchip_in_kernel(); + if (info->value->has_halted) { + info->value->halted =3D cpu->halted; + } + + 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/hmp-commands-info.hx b/hmp-commands-info.hx index ad590a4ffb..8657ceceb0 100644 --- a/hmp-commands-info.hx +++ b/hmp-commands-info.hx @@ -157,6 +157,20 @@ STEXI @item info cpus @findex info cpus Show infos for each CPU. +ETEXI + + { + .name =3D "cpus_fast", + .args_type =3D "", + .params =3D "", + .help =3D "show infos for each CPU without performance penal= ty", + .cmd =3D hmp_info_cpus_fast, + }, + +STEXI +@item info cpus_fast +@findex info cpus_fast +Show infos for each CPU without performance penalty. ETEXI =20 { diff --git a/hmp.c b/hmp.c index b3de32d219..3d32333fd2 100644 --- a/hmp.c +++ b/hmp.c @@ -404,6 +404,30 @@ void hmp_info_cpus(Monitor *mon, const QDict *qdict) qapi_free_CpuInfoList(cpu_list); } =20 +void hmp_info_cpus_fast(Monitor *mon, const QDict *qdict) +{ + CpuInfo2List *head, *cpu; + TargetInfo *target; + + target =3D qmp_query_target(NULL); + monitor_printf(mon, "CPU architecture is '%s'\n\n", target->arch); + qapi_free_TargetInfo(target); + + head =3D qmp_query_cpus_fast(NULL); + + for (cpu =3D head; cpu; cpu =3D cpu->next) { + monitor_printf(mon, "CPU%" PRId64 "\n", cpu->value->cpu_index); + monitor_printf(mon, " thread-id=3D%" PRId64 "\n", cpu->value->thre= ad_id); + if (cpu->value->has_halted) { + monitor_printf(mon, " halted=3D%d\n", cpu->value->halted); + } + monitor_printf(mon, " qom-path=3D%s\n", cpu->value->qom_path); + monitor_printf(mon, "\n"); + } + + qapi_free_CpuInfo2List(head); +} + static void print_block_info(Monitor *mon, BlockInfo *info, BlockDeviceInfo *inserted, bool verbose) { diff --git a/hmp.h b/hmp.h index 536cb91caa..f4ceba5cc8 100644 --- a/hmp.h +++ b/hmp.h @@ -31,6 +31,7 @@ void hmp_info_migrate_capabilities(Monitor *mon, const QD= ict *qdict); void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict); void hmp_info_migrate_cache_size(Monitor *mon, const QDict *qdict); void hmp_info_cpus(Monitor *mon, const QDict *qdict); +void hmp_info_cpus_fast(Monitor *mon, const QDict *qdict); void hmp_info_block(Monitor *mon, const QDict *qdict); void hmp_info_blockstats(Monitor *mon, const QDict *qdict); void hmp_info_vnc(Monitor *mon, const QDict *qdict); diff --git a/qapi-schema.json b/qapi-schema.json index 5c06745c79..82d6f12b53 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -558,6 +558,77 @@ ## { 'command': 'query-cpus', 'returns': ['CpuInfo'] } =20 +## +# @CpuInfo2: +# +# Information about a virtual CPU +# +# @cpu-index: index of the virtual CPU +# +# @halted: true if the virtual CPU is in the halt state. Halt usually ref= ers +# to a processor specific low power mode. This field is optional, +# it is only present if the halted state can be retrieved without +# a performance penalty +# +# @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 +# +# Notes: @halted is a transient state that changes frequently. By the tim= e the +# data is sent to the client, the guest may no longer be halted. +## +{ 'struct': 'CpuInfo2', + 'data': {'cpu-index': 'int', '*halted': 'bool', '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 @CpuInfo2 +# +# Notes: The CPU architecture name is not returned by query-cpus-fast. +# Use query-target to retreive 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': [ 'CpuInfo2' ] } + ## # @IOThreadInfo: # --=20 2.14.3 From nobody Sat Apr 27 15:35:33 2024 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 1518025933759499.96039701039274; Wed, 7 Feb 2018 09:52:13 -0800 (PST) Received: from localhost ([::1]:39185 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejTt6-0005rY-Mj for importer@patchew.org; Wed, 07 Feb 2018 12:52:04 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53150) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ejTrf-000551-D4 for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ejTrb-0002k1-RU for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:35 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:33784 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 1ejTrb-0002jX-ME for qemu-devel@nongnu.org; Wed, 07 Feb 2018 12:50:31 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1AE978A3DD; Wed, 7 Feb 2018 17:50:26 +0000 (UTC) Received: from localhost (ovpn-116-92.phx2.redhat.com [10.3.116.92]) by smtp.corp.redhat.com (Postfix) with ESMTP id B68E11006ED2; Wed, 7 Feb 2018 17:50:25 +0000 (UTC) From: Luiz Capitulino To: qemu-devel@nongnu.org Date: Wed, 7 Feb 2018 12:50:14 -0500 Message-Id: <20180207175014.11157-3-lcapitulino@redhat.com> In-Reply-To: <20180207175014.11157-1-lcapitulino@redhat.com> References: <20180207175014.11157-1-lcapitulino@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 07 Feb 2018 17:50:26 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 07 Feb 2018 17:50:26 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'lcapitulino@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] [PATCH 2/2] qmp: document query-cpus performance issue 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: mihajlov@linux.vnet.ibm.com, armbru@redhat.com, ehabkost@redhat.com 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" Signed-off-by: Luiz Capitulino Acked-by: Eric Blake --- qapi-schema.json | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/qapi-schema.json b/qapi-schema.json index 82d6f12b53..0665a14dba 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -526,6 +526,10 @@ # # Returns a list of information about each virtual CPU. # +# WARNING: This command incurs a performance penalty for latency +# sensitive workloads and hence it's not recommended to +# to be used in production. Use query-cpus-fast instead +# # Returns: a list of @CpuInfo for each virtual CPU # # Since: 0.14.0 --=20 2.14.3