From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 22A52C433EF for ; Mon, 16 May 2022 12:41:41 +0000 (UTC) Received: from localhost ([::1]:51090 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nqa2d-0006kE-Lz for qemu-devel@archiver.kernel.org; Mon, 16 May 2022 08:41:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36694) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nqZOn-0007Ji-7V for qemu-devel@nongnu.org; Mon, 16 May 2022 08:00:30 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24715) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nqZOg-0002aj-8O for qemu-devel@nongnu.org; Mon, 16 May 2022 08:00:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652702421; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3E4zapaMHpbkrJ8zRfCcMoDXt8dlxhArODIdulJe0kg=; b=hfFcRoX2U8Hbf6gq844r6/L6eqdMDqXN2laGxNlxkzsxRCXzbzXY71zNBJAeGT1a55Pujw SOOVmpasFcomPYQkuLP7nhdaTTridPu0IGIv0sngA84K3bhiJlY6MSVwAvAUJh3IR4R1IU C1gCeq2HpNVZbF8GJVFtg4QgPTzPzzk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-176-6i2dISkNObSPGCV45OWpuA-1; Mon, 16 May 2022 08:00:18 -0400 X-MC-Unique: 6i2dISkNObSPGCV45OWpuA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B616080CDA6; Mon, 16 May 2022 12:00:17 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.36.112.4]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 595BB438BFA; Mon, 16 May 2022 12:00:17 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 38B6C21E690D; Mon, 16 May 2022 14:00:16 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini Cc: qemu-devel@nongnu.org, armbru@redhat.com, berrange@redhat.com, dgilbert@redhat.com, Mark Kanda Subject: Re: [PATCH v3 1/8] qmp: Support for querying stats References: <20220516090058.1195767-1-pbonzini@redhat.com> <20220516090058.1195767-2-pbonzini@redhat.com> Date: Mon, 16 May 2022 14:00:16 +0200 In-Reply-To: <20220516090058.1195767-2-pbonzini@redhat.com> (Paolo Bonzini's message of "Mon, 16 May 2022 11:00:51 +0200") Message-ID: <87pmkdy9f3.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > From: Mark Kanda > > Gathering statistics is important for development, for monitoring and > for performance measurement. There are tools such as kvm_stat that do > this and they rely on the _user_ knowing the interesting data points > rather than the tool (which can treat them as opaque). > > The commands introduced in this commit introduce QMP support for > querying stats; the goal is to take the capabilities of these tools > and making them available throughout the whole virtualization stack, > so that one can observe, monitor and measure virtual machines without > having shell access + root on the host that runs them. > > query-stats returns a list of all stats per target type (only VM > and vCPU to start); future commits add extra options for specifying > stat names, vCPU qom paths, and providers. All these are used by the > HMP command "info stats". Because of the development usecases around > statistics, a good HMP interface is important. > > query-stats-schemas returns a list of stats included in each target > type, with an option for specifying the provider. The concepts in the > schema are based on the KVM binary stats' own introspection data, just > translated to QAPI. > > There are two reasons to have a separate schema that is not tied to > the QAPI schema. The first is the contents of the schemas: the new > introspection data provides different information than the QAPI data, > namely unit of measurement, how the numbers are gathered and change > (peak/instant/cumulative/histogram), and histogram bucket sizes. > There's really no reason to have this kind of metadata in the QAPI > introspection schema (except possibly for the unit of measure, but > there's a very weak justification). > > Another reason is the dynamicity of the schema. The QAPI introspection > data is very much static; and while QOM is somewhat more dynamic, > generally we consider that to be a bug rather than a feature these days. > On the other hand, the statistics that are exposed by QEMU might be > passed through from another source, such as KVM, and the disadvantages of > manually updating the QAPI schema for outweight the benefits from vetting > the statistics and filtering out anything that seems "too unstable". > Running old QEMU with new kernel is a supported usecase; if old QEMU > cannot expose statistics from a new kernel, or if a kernel developer > needs to change QEMU before gathering new info from the new kernel, > then that is a poor user interface. > > The framework provides a method to register callbacks for these QMP > commands. Most of the work in fact is done by the callbacks, and a > large majority of this patch is new QAPI structs and commands. Nice! > Examples (with KVM stats): > > - Query all VM stats: > > { "execute": "query-stats", "arguments" : { "target": "vm" } } > > { "return": [ > { "provider": "kvm", > "stats": [ > { "name": "max_mmu_page_hash_collisions", "value": 0 }, > { "name": "max_mmu_rmap_size", "value": 0 }, > { "name": "nx_lpage_splits", "value": 148 }, > ... ] }, > { "provider": "xyz", > "stats": [ ... ] } > ] } > > - Query all vCPU stats: > > { "execute": "query-stats", "arguments" : { "target": "vcpu" } } > > { "return": [ > { "provider": "kvm", > "qom_path": "/machine/unattached/device[0]" > "stats": [ > { "name": "guest_mode", "value": 0 }, > { "name": "directed_yield_successful", "value": 0 }, > { "name": "directed_yield_attempted", "value": 106 }, > ... ] }, > { "provider": "kvm", > "qom_path": "/machine/unattached/device[1]" > "stats": [ > { "name": "guest_mode", "value": 0 }, > { "name": "directed_yield_successful", "value": 0 }, > { "name": "directed_yield_attempted", "value": 106 }, > ... ] }, > ] } > > - Retrieve the schemas: > > { "execute": "query-stats-schemas" } > > { "return": [ > { "provider": "kvm", > "target": "vcpu", > "stats": [ > { "name": "guest_mode", > "unit": "none", > "base": 10, > "exponent": 0, > "type": "instant" }, > { "name": "directed_yield_successful", > "unit": "none", > "base": 10, > "exponent": 0, > "type": "cumulative" }, > ... ] > }, > { "provider": "kvm", > "target": "vm", > "stats": [ > { "name": "max_mmu_page_hash_collisions", > "unit": "none", > "base": 10, > "exponent": 0, > "type": "peak" }, > ... ] > }, > { "provider": "xyz", > "target": "vm", > "stats": [ ... ] > } > ] } > > Signed-off-by: Mark Kanda > Signed-off-by: Paolo Bonzini > --- > include/monitor/stats.h | 33 ++++++ > monitor/qmp-cmds.c | 71 +++++++++++++ > qapi/meson.build | 1 + > qapi/qapi-schema.json | 1 + > qapi/stats.json | 215 ++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 321 insertions(+) > create mode 100644 include/monitor/stats.h > create mode 100644 qapi/stats.json > > diff --git a/include/monitor/stats.h b/include/monitor/stats.h > new file mode 100644 > index 0000000000..89552ab06f > --- /dev/null > +++ b/include/monitor/stats.h > @@ -0,0 +1,33 @@ > +/* > + * Copyright (c) 2022 Oracle and/or its affiliates. > + * > + * This work is licensed under the terms of the GNU GPL, version 2. > + * See the COPYING file in the top-level directory. > + */ > + > +#ifndef STATS_H > +#define STATS_H > + > +#include "qapi/qapi-types-stats.h" > + > +typedef void StatRetrieveFunc(StatsResultList **result, StatsTarget target, Error **errp); Long line. > +typedef void SchemaRetrieveFunc(StatsSchemaList **result, Error **errp); > + > +/* > + * Register callbacks for the QMP query-stats command. > + * > + * @stats_fn: routine to query stats: > + * @schema_fn: routine to query stat schemas: > + */ > +void add_stats_callbacks(StatRetrieveFunc *stats_fn, > + SchemaRetrieveFunc *schemas_fn); > + > +/* > + * Helper routines for adding stats entries to the results lists. > + */ > +void add_stats_entry(StatsResultList **, StatsProvider, const char *id, > + StatsList *stats_list); > +void add_stats_schema(StatsSchemaList **, StatsProvider, StatsTarget, > + StatsSchemaValueList *); > + > +#endif /* STATS_H */ > diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c > index 1ebb89f46c..d83faeca88 100644 > --- a/monitor/qmp-cmds.c > +++ b/monitor/qmp-cmds.c > @@ -35,6 +35,7 @@ > #include "qapi/qapi-commands-control.h" > #include "qapi/qapi-commands-machine.h" > #include "qapi/qapi-commands-misc.h" > +#include "qapi/qapi-commands-stats.h" > #include "qapi/qapi-commands-ui.h" > #include "qapi/type-helpers.h" > #include "qapi/qmp/qerror.h" > @@ -43,6 +44,7 @@ > #include "hw/acpi/acpi_dev_interface.h" > #include "hw/intc/intc.h" > #include "hw/rdma/rdma.h" > +#include "monitor/stats.h" > > NameInfo *qmp_query_name(Error **errp) > { > @@ -441,3 +443,72 @@ HumanReadableText *qmp_x_query_irq(Error **errp) > > return human_readable_text_from_str(buf); > } > + > +typedef struct StatsCallbacks { > + StatRetrieveFunc *stats_cb; > + SchemaRetrieveFunc *schemas_cb; > + QTAILQ_ENTRY(StatsCallbacks) next; > +} StatsCallbacks; > + > +static QTAILQ_HEAD(, StatsCallbacks) stats_callbacks = > + QTAILQ_HEAD_INITIALIZER(stats_callbacks); > + > +void add_stats_callbacks(StatRetrieveFunc *stats_fn, > + SchemaRetrieveFunc *schemas_fn) > +{ > + StatsCallbacks *entry = g_new(StatsCallbacks, 1); > + entry->stats_cb = stats_fn; > + entry->schemas_cb = schemas_fn; > + > + QTAILQ_INSERT_TAIL(&stats_callbacks, entry, next); > +} > + > +StatsResultList *qmp_query_stats(StatsFilter *filter, Error **errp) > +{ > + StatsResultList *stats_results = NULL; > + StatsCallbacks *entry; > + > + QTAILQ_FOREACH(entry, &stats_callbacks, next) { > + entry->stats_cb(&stats_results, filter->target, errp); If more than one of these sets an error, then the second error_setg() will trip error_setv()'s assertion. What's the callback's contract? > + } > + > + return stats_results; > +} > + > +StatsSchemaList *qmp_query_stats_schemas(Error **errp) > +{ > + StatsSchemaList *stats_results = NULL; > + StatsCallbacks *entry; > + > + QTAILQ_FOREACH(entry, &stats_callbacks, next) { > + entry->schemas_cb(&stats_results, errp); Likewise. > + } > + > + return stats_results; > +} > + > +void add_stats_entry(StatsResultList **stats_results, StatsProvider provider, > + const char *qom_path, StatsList *stats_list) > +{ > + StatsResult *entry = g_new0(StatsResult, 1); Suggest blank line between declarations and statements, like in the next function. > + entry->provider = provider; > + if (qom_path) { > + entry->has_qom_path = true; > + entry->qom_path = g_strdup(qom_path); > + } > + entry->stats = stats_list; > + > + QAPI_LIST_PREPEND(*stats_results, entry); > +} > + > +void add_stats_schema(StatsSchemaList **schema_results, > + StatsProvider provider, StatsTarget target, > + StatsSchemaValueList *stats_list) > +{ > + StatsSchema *entry = g_new0(StatsSchema, 1); > + > + entry->provider = provider; > + entry->target = target; > + entry->stats = stats_list; > + QAPI_LIST_PREPEND(*schema_results, entry); > +} The order of elements doesn't matter in either list, right? > diff --git a/qapi/meson.build b/qapi/meson.build > index 656ef0e039..fd5c93d643 100644 > --- a/qapi/meson.build > +++ b/qapi/meson.build > @@ -46,6 +46,7 @@ qapi_all_modules = [ > 'replay', > 'run-state', > 'sockets', > + 'stats', > 'trace', > 'transaction', > 'yank', > diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json > index 4912b9744e..92d7ecc52c 100644 > --- a/qapi/qapi-schema.json > +++ b/qapi/qapi-schema.json > @@ -93,3 +93,4 @@ > { 'include': 'audio.json' } > { 'include': 'acpi.json' } > { 'include': 'pci.json' } > +{ 'include': 'stats.json' } > diff --git a/qapi/stats.json b/qapi/stats.json > new file mode 100644 > index 0000000000..f0656a6435 > --- /dev/null > +++ b/qapi/stats.json > @@ -0,0 +1,215 @@ > +# -*- Mode: Python -*- > +# vim: filetype=python > +# > +# Copyright (c) 2022 Oracle and/or its affiliates. > +# > +# This work is licensed under the terms of the GNU GPL, version 2 or later. > +# See the COPYING file in the top-level directory. > +# > +# SPDX-License-Identifier: GPL-2.0-or-later > + > +## > +# = Statistics > +## > + > +## > +# @StatsType: > +# > +# Enumeration of statistics types > +# > +# @cumulative: stat is cumulative; value can only increase. > +# @instant: stat is instantaneous; value can increase or decrease. > +# @peak: stat is the peak value; value can only increase. > +# @linear-histogram: stat is a linear histogram. > +# @log2-histogram: stat is a logarithmic histogram, with one bucket > +# for each power of two. > +# > +# Since: 7.1 > +## > +{ 'enum' : 'StatsType', > + 'data' : [ 'cumulative', 'instant', 'peak', 'linear-histogram', 'log2-histogram' ] } Long line. > + > +## > +# @StatsUnit: > +# > +# Enumeration of unit of measurement for statistics > +# > +# @bytes: stat reported in bytes. > +# @seconds: stat reported in seconds. > +# @cycles: stat reported in clock cycles. > +# > +# Since: 7.1 > +## > +{ 'enum' : 'StatsUnit', > + 'data' : [ 'bytes', 'seconds', 'cycles' ] } > + > +## > +# @StatsProvider: > +# > +# Enumeration of statistics providers. > +# > +# Since: 7.1 > +## > +{ 'enum': 'StatsProvider', > + 'data': [ ] } > + > +## > +# @StatsTarget: > +# > +# The kinds of objects on which one can request statistics. > +# > +# @vm: statistics that apply to the entire virtual machine or > +# the entire QEMU process. > +# > +# @vcpu: statistics that apply to a single virtual CPU. > +# > +# Since: 7.1 > +## > +{ 'enum': 'StatsTarget', > + 'data': [ 'vm', 'vcpu' ] } > + > +## > +# @StatsFilter: > +# > +# The arguments to the query-stats command; specifies a target for which to > +# request statistics. > +# > +# Since: 7.1 > +## > +{ 'struct': 'StatsFilter', > + 'data': { 'target': 'StatsTarget' } } > + > +## > +# @StatsValue: > +# > +# @scalar: single unsigned 64-bit integers. > +# @list: list of unsigned 64-bit integers (used for histograms). > +# > +# Since: 7.1 > +## > +{ 'alternate': 'StatsValue', > + 'data': { 'scalar': 'uint64', > + 'list': [ 'uint64' ] } } > + > +## > +# @Stats: > +# > +# @name: name of stat. > +# @value: stat value. > +# > +# Since: 7.1 > +## > +{ 'struct': 'Stats', > + 'data': { 'name': 'str', > + 'value' : 'StatsValue' } } > + > +## > +# @StatsResult: > +# > +# @provider: provider for this set of statistics. > +# > +# @qom-path: Path to the object for which the statistics are returned, > +# if the object is exposed in the QOM tree > +# > +# @stats: list of statistics. > +# > +# Since: 7.1 > +## > +{ 'struct': 'StatsResult', > + 'data': { 'provider': 'StatsProvider', > + '*qom-path': 'str', > + 'stats': [ 'Stats' ] } } > + > +## > +# @query-stats: > +# > +# Return runtime-collected statistics for objects such as the > +# VM or its vCPUs. > +# > +# The arguments are a StatsFilter and specify the provider and objects > +# to return statistics about. > +# > +# Returns: a list of StatsResult, one for each provider and object > +# (e.g., for each vCPU). > +# > +# Since: 7.1 > +## > +{ 'command': 'query-stats', > + 'data': 'StatsFilter', > + 'boxed': true, > + 'returns': [ 'StatsResult' ] } > + > +## > +# @StatsSchemaValue: > +# > +# Schema for a single statistic. > +# > +# @name: name of the statistic; each element of the schema is uniquely > +# identified by a target, a provider (both available in @StatsSchema) > +# and the name. > +# > +# @type: kind of statistic. > +# > +# @unit: basic unit of measure for the statistic; if missing, the statistic > +# is a simple number or counter. > +# > +# @base: base for the multiple of @unit in which the statistic is measured. > +# Only present if @exponent is non-zero; @base and @exponent together > +# form a SI prefix (e.g., _nano-_ for ``base=10`` and ``exponent=-9``) > +# or IEC binary prefix (e.g. _kibi-_ for ``base=2`` and ``exponent=10``) > +# > +# @exponent: exponent for the multiple of @unit in which the statistic is > +# expressed, or 0 for the basic unit > +# > +# @bucket-size: Present when @type is "linear-histogram", contains the width > +# of each bucket of the histogram. > +# > +# Since: 7.1 > +## > +{ 'struct': 'StatsSchemaValue', > + 'data': { 'name': 'str', > + 'type': 'StatsType', > + '*unit': 'StatsUnit', > + '*base': 'int8', > + 'exponent': 'int16', > + '*bucket-size': 'uint32' } } > + > +## > +# @StatsSchema: > +# > +# Schema for all available statistics for a provider and target. > +# > +# @provider: provider for this set of statistics. > +# > +# @target: the kind of object that can be queried through the provider. > +# > +# @stats: list of statistics. > +# > +# Since: 7.1 > +## > +{ 'struct': 'StatsSchema', > + 'data': { 'provider': 'StatsProvider', > + 'target': 'StatsTarget', > + 'stats': [ 'StatsSchemaValue' ] } } > + > +## > +# @query-stats-schemas: > +# > +# Return the schema for all available runtime-collected statistics. > +# > +# Note: runtime-collected statistics and their names fall outside QEMU's > +# usual deprecation policies. QEMU will try to keep the set of available > +# data stable, together with their names, but will not guarantee stability > +# at all costs; the same is true of providers that source statistics > +# externally, e.g. from Linux. For example, if the same value is being > +# tracked with different names on different architectures or by different > +# providers, one of them might be renamed. A statistic might go away if > +# an algorithm is changed or some code is removed; changing a default might > +# cause previously useful statistics to always report 0. Such changes, > +# however, they are expected to be rare. Scratch "they". > +# > +# Since: 7.1 > +## > +{ 'command': 'query-stats-schemas', > + 'data': { }, > + 'returns': [ 'StatsSchema' ] }