Re: [PATCH RFC v2 3/3] qemu_driver: use qemuMonitorQueryStats to extract halt poll time
On Wed, Jul 06, 2022 at 04:56:28AM +0530, Amneesh Singh wrote:
Related: https://gitlab.com/libvirt/libvirt/-/issues/276
This patch uses qemuMonitorQueryStats to query "halt_poll_success_ns"
and "halt_poll_fail_ns" for every vCPU. The respective values for each
vCPU are then added together.
Signed-off-by: Amneesh Singh
---
src/qemu/qemu_driver.c | 70 +-
1 file changed, 62 insertions(+), 8 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 97c6ed95..30170d5c 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18052,15 +18052,69 @@ qemuDomainGetStatsCpuCgroup(virDomainObj *dom,
}
static int
-qemuDomainGetStatsCpuHaltPollTime(virDomainObj *dom,
- virTypedParamList *params)
+qemuDomainGetStatsCpuHaltPollTime(virQEMUDriver *driver,
+ virDomainObj *dom,
+ virTypedParamList *params,
+ unsigned int privflags)
{
unsigned long long haltPollSuccess = 0;
unsigned long long haltPollFail = 0;
-pid_t pid = dom->pid;
+qemuDomainObjPrivate *priv = dom->privateData;
+bool queryStatsCap = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_QUERY_STATS);
-if (virHostCPUGetHaltPollTime(pid, &haltPollSuccess, &haltPollFail) < 0)
-return 0;
+if (queryStatsCap && HAVE_JOB(privflags) && virDomainObjIsActive(dom) &&
driver->privileged) {
Why is there a check for whether the driver is privileged? I thought
this can also work with a session mode.
+size_t i;
+qemuMonitorQueryStatsTargetType target =
QEMU_MONITOR_QUERY_STATS_TARGET_VCPU;
+qemuMonitorQueryStatsProvider *provider = NULL;
+g_autoptr(GPtrArray) providers = NULL;
+g_autoptr(GPtrArray) queried_stats = NULL;
+provider = qemuMonitorQueryStatsProviderNew(
+target,
+QEMU_MONITOR_QUERY_STATS_PROVIDER_KVM,
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_SUCCESS_NS,
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_FAIL_NS,
+-1);
+
+if (!provider)
+return 0;
In this case you can still do the callback. Basically don't put it in
an "else" branch, just get a new condition checking if the stats were
gathered or not (if need be you can get a new variable for that).
+
+providers = g_ptr_array_new_full(1, (GDestroyNotify)
qemuMonitorQueryStatsProviderFree);
+g_ptr_array_add(providers, provider);
+
+qemuDomainObjEnterMonitor(driver, dom);
+queried_stats = qemuMonitorQueryStats(priv->mon, target, NULL,
providers);
+qemuDomainObjExitMonitor(dom);
+
+if (!queried_stats)
+return 0;
+
+for (i = 0; i < queried_stats->len; i++) {
+unsigned long long curHaltPollSuccess, curHaltPollFail;
+GHashTable *cur_table = queried_stats->pdata[i];
+virJSONValue *success_obj, *fail_obj;
+const char *success_str =
qemuMonitorQueryStatsVcpuNameTypeToString(
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_SUCCESS_NS);
+const char *fail_str = qemuMonitorQueryStatsVcpuNameTypeToString(
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_FAIL_NS);
+
+success_obj = g_hash_table_lookup(cur_table, success_str);
+fail_obj = g_hash_table_lookup(cur_table, fail_str);
+
If you want it could be nicer to have an extra function for this since
it looks like it'll be repeated. Also have a look if the enums can't be
defined elsewhere/differently so that you can end up with something like
this:
virJSONValue *success_obj = qemuStatsGet(QEMU_STATS_NAME_HALT_POLL_SUCCESS_NS);
+if (!(success_obj && fail_obj))
+return 0;
+
This checks if they both exist (although I would prefer (!success_obj ||
!fail_obj) as it is more readable and for me it is similar to how I
would say that in a sentence) but does not check that they really are a
number.
+ignore_value(virJSONValueGetNumberUlong(success_obj,
&curHaltPollSuccess));
+ignore_value(virJSONValueGetNumberUlong(fail_obj,
&curHaltPollFail));
+
That's why you should also check that the virJSONValueGetNumberUlong
does not return -1. That's why it makes you use the return value.
Also these are another cases where you can execute the fallback instead.
Thanks for taking the time to polish this.
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[PATCH RFC v2 3/3] qemu_driver: use qemuMonitorQueryStats to extract halt poll time
Related: https://gitlab.com/libvirt/libvirt/-/issues/276
This patch uses qemuMonitorQueryStats to query "halt_poll_success_ns"
and "halt_poll_fail_ns" for every vCPU. The respective values for each
vCPU are then added together.
Signed-off-by: Amneesh Singh
---
src/qemu/qemu_driver.c | 70 +-
1 file changed, 62 insertions(+), 8 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 97c6ed95..30170d5c 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18052,15 +18052,69 @@ qemuDomainGetStatsCpuCgroup(virDomainObj *dom,
}
static int
-qemuDomainGetStatsCpuHaltPollTime(virDomainObj *dom,
- virTypedParamList *params)
+qemuDomainGetStatsCpuHaltPollTime(virQEMUDriver *driver,
+ virDomainObj *dom,
+ virTypedParamList *params,
+ unsigned int privflags)
{
unsigned long long haltPollSuccess = 0;
unsigned long long haltPollFail = 0;
-pid_t pid = dom->pid;
+qemuDomainObjPrivate *priv = dom->privateData;
+bool queryStatsCap = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_QUERY_STATS);
-if (virHostCPUGetHaltPollTime(pid, &haltPollSuccess, &haltPollFail) < 0)
-return 0;
+if (queryStatsCap && HAVE_JOB(privflags) && virDomainObjIsActive(dom) &&
driver->privileged) {
+size_t i;
+qemuMonitorQueryStatsTargetType target =
QEMU_MONITOR_QUERY_STATS_TARGET_VCPU;
+qemuMonitorQueryStatsProvider *provider = NULL;
+g_autoptr(GPtrArray) providers = NULL;
+g_autoptr(GPtrArray) queried_stats = NULL;
+provider = qemuMonitorQueryStatsProviderNew(
+target,
+QEMU_MONITOR_QUERY_STATS_PROVIDER_KVM,
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_SUCCESS_NS,
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_FAIL_NS,
+-1);
+
+if (!provider)
+return 0;
+
+providers = g_ptr_array_new_full(1, (GDestroyNotify)
qemuMonitorQueryStatsProviderFree);
+g_ptr_array_add(providers, provider);
+
+qemuDomainObjEnterMonitor(driver, dom);
+queried_stats = qemuMonitorQueryStats(priv->mon, target, NULL,
providers);
+qemuDomainObjExitMonitor(dom);
+
+if (!queried_stats)
+return 0;
+
+for (i = 0; i < queried_stats->len; i++) {
+unsigned long long curHaltPollSuccess, curHaltPollFail;
+GHashTable *cur_table = queried_stats->pdata[i];
+virJSONValue *success_obj, *fail_obj;
+const char *success_str =
qemuMonitorQueryStatsVcpuNameTypeToString(
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_SUCCESS_NS);
+const char *fail_str = qemuMonitorQueryStatsVcpuNameTypeToString(
+QEMU_MONITOR_QUERY_STATS_VCPU_NAME_HALT_POLL_FAIL_NS);
+
+success_obj = g_hash_table_lookup(cur_table, success_str);
+fail_obj = g_hash_table_lookup(cur_table, fail_str);
+
+if (!(success_obj && fail_obj))
+return 0;
+
+ignore_value(virJSONValueGetNumberUlong(success_obj,
&curHaltPollSuccess));
+ignore_value(virJSONValueGetNumberUlong(fail_obj,
&curHaltPollFail));
+
+haltPollSuccess += curHaltPollSuccess;
+haltPollFail += curHaltPollFail;
+}
+} else {
+pid_t pid = dom->pid;
+
+if (virHostCPUGetHaltPollTime(pid, &haltPollSuccess, &haltPollFail) <
0)
+return 0;
+}
if (virTypedParamListAddULLong(params, haltPollSuccess,
"cpu.haltpoll.success.time") < 0 ||
virTypedParamListAddULLong(params, haltPollFail,
"cpu.haltpoll.fail.time") < 0)
@@ -18073,7 +18127,7 @@ static int
qemuDomainGetStatsCpu(virQEMUDriver *driver,
virDomainObj *dom,
virTypedParamList *params,
- unsigned int privflags G_GNUC_UNUSED)
+ unsigned int privflags)
{
if (qemuDomainGetStatsCpuCgroup(dom, params) < 0)
return -1;
@@ -18081,7 +18135,7 @@ qemuDomainGetStatsCpu(virQEMUDriver *driver,
if (qemuDomainGetStatsCpuCache(driver, dom, params) < 0)
return -1;
-if (qemuDomainGetStatsCpuHaltPollTime(dom, params) < 0)
+if (qemuDomainGetStatsCpuHaltPollTime(driver, dom, params, privflags) < 0)
return -1;
return 0;
@@ -18915,7 +18969,7 @@ static virQEMUCapsFlags queryDirtyRateRequired[] = {
static struct qemuDomainGetStatsWorker qemuDomainGetStatsWorkers[] = {
{ qemuDomainGetStatsState, VIR_DOMAIN_STATS_STATE, false, NULL },
-{ qemuDomainGetStatsCpu, VIR_DOMAIN_STATS_CPU_TOTAL, false, NULL },
+{ qemuDomainGetStatsCpu, VIR_DOMAIN_STATS_CPU_TOTAL, true, NULL },
{ qemuDomainGetStatsBalloon, VIR_DOMAIN_STATS_BALLOON, true, NULL },
{ qemuDomainGetStatsVcpu, VIR_DOMAIN_STATS_VCPU, true, NULL },
