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[PATCH 7/8] qmp: add filtering of statistics by name
From: |
Paolo Bonzini |
Subject: |
[PATCH 7/8] qmp: add filtering of statistics by name |
Date: |
Mon, 23 May 2022 17:07:21 +0200 |
Allow retrieving only a subset of statistics. This can be useful
for example in order to plot a subset of the statistics many times
a second.
KVM publishes ~40 statistics for each vCPU on x86; retrieving and
serializing all of them would be useless
Another use will be in HMP in the following patch; implementing the
filter in the backend is easy enough that it was deemed okay to make
this a public interface.
Example:
{ "execute": "query-stats",
"arguments": {
"target": "vcpu",
"vcpus": [ "/machine/unattached/device[2]",
"/machine/unattached/device[4]" ],
"providers": [
{ "provider": "kvm",
"names": [ "l1d_flush", "exits" ] } } }
{ "return": {
"vcpus": [
{ "path": "/machine/unattached/device[2]"
"providers": [
{ "provider": "kvm",
"stats": [ { "name": "l1d_flush", "value": 41213 },
{ "name": "exits", "value": 74291 } ] } ] },
{ "path": "/machine/unattached/device[4]"
"providers": [
{ "provider": "kvm",
"stats": [ { "name": "l1d_flush", "value": 16132 },
{ "name": "exits", "value": 57922 } ] } ] } ] } }
Extracted from a patch by Mark Kanda.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
v3->v4: handle empty filter early by avoiding the query altogether
accel/kvm/kvm-all.c | 17 +++++++++++------
include/monitor/stats.h | 4 ++--
monitor/qmp-cmds.c | 16 +++++++++++++---
qapi/stats.json | 6 +++++-
4 files changed, 31 insertions(+), 12 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 461b6cf927..a61d17719e 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2311,7 +2311,7 @@ bool kvm_dirty_ring_enabled(void)
return kvm_state->kvm_dirty_ring_size ? true : false;
}
-static void query_stats_cb(StatsResultList **result, StatsTarget target,
+static void query_stats_cb(StatsResultList **result, StatsTarget target,
strList *names,
strList *targets, Error **errp);
static void query_stats_schemas_cb(StatsSchemaList **result, Error **errp);
@@ -3713,6 +3713,7 @@ typedef struct StatsArgs {
StatsResultList **stats;
StatsSchemaList **schema;
} result;
+ strList *names;
Error **errp;
} StatsArgs;
@@ -3926,7 +3927,7 @@ static StatsDescriptors
*find_stats_descriptors(StatsTarget target, int stats_fd
return descriptors;
}
-static void query_stats(StatsResultList **result, StatsTarget target,
+static void query_stats(StatsResultList **result, StatsTarget target, strList
*names,
int stats_fd, Error **errp)
{
struct kvm_stats_desc *kvm_stats_desc;
@@ -3969,6 +3970,9 @@ static void query_stats(StatsResultList **result,
StatsTarget target,
/* Add entry to the list */
stats = (void *)stats_data + pdesc->offset;
+ if (!apply_str_list_filter(pdesc->name, names)) {
+ continue;
+ }
stats_list = add_kvmstat_entry(pdesc, stats, stats_list, errp);
}
@@ -4030,8 +4034,8 @@ static void query_stats_vcpu(CPUState *cpu,
run_on_cpu_data data)
error_propagate(kvm_stats_args->errp, local_err);
return;
}
- query_stats(kvm_stats_args->result.stats, STATS_TARGET_VCPU, stats_fd,
- kvm_stats_args->errp);
+ query_stats(kvm_stats_args->result.stats, STATS_TARGET_VCPU,
+ kvm_stats_args->names, stats_fd, kvm_stats_args->errp);
close(stats_fd);
}
@@ -4052,7 +4056,7 @@ static void query_stats_schema_vcpu(CPUState *cpu,
run_on_cpu_data data)
}
static void query_stats_cb(StatsResultList **result, StatsTarget target,
- strList *targets, Error **errp)
+ strList *names, strList *targets, Error **errp)
{
KVMState *s = kvm_state;
CPUState *cpu;
@@ -4066,7 +4070,7 @@ static void query_stats_cb(StatsResultList **result,
StatsTarget target,
error_setg(errp, "KVM stats: ioctl failed");
return;
}
- query_stats(result, target, stats_fd, errp);
+ query_stats(result, target, names, stats_fd, errp);
close(stats_fd);
break;
}
@@ -4074,6 +4078,7 @@ static void query_stats_cb(StatsResultList **result,
StatsTarget target,
{
StatsArgs stats_args;
stats_args.result.stats = result;
+ stats_args.names = names;
stats_args.errp = errp;
CPU_FOREACH(cpu) {
if (!apply_str_list_filter(cpu->parent_obj.canonical_path,
targets)) {
diff --git a/include/monitor/stats.h b/include/monitor/stats.h
index 840c4ed08e..88f046f568 100644
--- a/include/monitor/stats.h
+++ b/include/monitor/stats.h
@@ -11,8 +11,8 @@
#include "qapi/qapi-types-stats.h"
typedef void StatRetrieveFunc(StatsResultList **result, StatsTarget target,
- strList *targets, Error **errp);
-typedef void SchemaRetrieveFunc(StatsSchemaList **result, Error **errp);
+ strList *names, strList *targets, Error **errp);
+typedef void SchemaRetrieveFunc(StatsSchemaList **, Error **);
/*
* Register callbacks for the QMP query-stats command.
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index 7be0e7414a..e822f1b0a9 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -467,15 +467,24 @@ void add_stats_callbacks(StatsProvider provider,
}
static bool stats_provider_requested(StatsProvider provider,
- StatsFilter *filter)
+ StatsFilter *filter,
+ strList **p_names)
{
StatsRequestList *request;
+ *p_names = NULL;
if (!filter->has_providers) {
return true;
}
for (request = filter->providers; request; request = request->next) {
if (request->value->provider == provider) {
+ if (request->value->has_names) {
+ if (!request->value->names) {
+ /* No names allowed is the same as skipping the provider.
*/
+ return false;
+ }
+ *p_names = request->value->names;
+ }
return true;
}
}
@@ -506,8 +515,9 @@ StatsResultList *qmp_query_stats(StatsFilter *filter, Error
**errp)
}
QTAILQ_FOREACH(entry, &stats_callbacks, next) {
- if (stats_provider_requested(entry->provider, filter)) {
- entry->stats_cb(&stats_results, filter->target, targets, errp);
+ strList *names = NULL;
+ if (stats_provider_requested(entry->provider, filter, &names)) {
+ entry->stats_cb(&stats_results, filter->target, names, targets,
errp);
if (*errp) {
qapi_free_StatsResultList(stats_results);
return NULL;
diff --git a/qapi/stats.json b/qapi/stats.json
index b75bb86124..2dbf188d36 100644
--- a/qapi/stats.json
+++ b/qapi/stats.json
@@ -74,11 +74,14 @@
# Indicates a set of statistics that should be returned by query-stats.
#
# @provider: provider for which to return statistics.
+
+# @names: statistics to be returned (all if omitted).
#
# Since: 7.1
##
{ 'struct': 'StatsRequest',
- 'data': { 'provider': 'StatsProvider' } }
+ 'data': { 'provider': 'StatsProvider',
+ '*names': [ 'str' ] } }
##
# @StatsVCPUFilter:
@@ -98,6 +101,7 @@
# that target:
# - which vCPUs to request statistics for
# - which provider to request statistics from
+# - which values to return within each provider
#
# Since: 7.1
##
--
2.36.0
[PATCH 3/8] qmp: add filtering of statistics by target vCPU, Paolo Bonzini, 2022/05/23
Re: [PATCH 1/8] qmp: Support for querying stats, Markus Armbruster, 2022/05/24
Re: [PATCH 1/8] qmp: Support for querying stats, Markus Armbruster, 2022/05/24