8:41 a.m.
The VIR_DOMAIN_STATS_VCPU flag to virDomainListGetStats
enables reporting of stats about vCPUs. Currently we
only report the cumulative CPU running time and the
execution state.
This adds reporting of the wait time - time the vCPU
wants to run, but the host schedular has something else
running ahead of it.
The data is reported per-vCPU eg
$ virsh domstats --vcpu demo
Domain: 'demo'
vcpu.current=4
vcpu.maximum=4
vcpu.0.state=1
vcpu.0.time=1420000000
vcpu.0.wait=18403928
vcpu.1.state=1
vcpu.1.time=130000000
vcpu.1.wait=10612111
vcpu.2.state=1
vcpu.2.time=110000000
vcpu.2.wait=12759501
vcpu.3.state=1
vcpu.3.time=90000000
vcpu.3.wait=21825087
In implementing this I notice our reporting of CPU execute
time has very poor granularity, since we are getting it
from /proc/$PID/stat. As a future enhancement we should
prefer to get CPU execute time from /proc/$PID/schedstat
or /proc/$PID/sched (if either exist on the running kernel)
Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com>
---
src/qemu/qemu_driver.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 96 insertions(+), 4 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 783a7cd..5293294 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1361,6 +1361,80 @@ static char *qemuConnectGetCapabilities(virConnectPtr conn) {
static int
+qemuGetSchedInfo(unsigned long long *cpuWait,
+ pid_t pid, pid_t tid)
+{
+ char *proc = NULL;
+ char *data = NULL;
+ char **lines = NULL;
+ size_t i;
+ int ret = -1;
+ double val;
+
+ *cpuWait = 0;
+
+ /* In general, we cannot assume pid_t fits in int; but /proc parsing
+ * is specific to Linux where int works fine. */
+ if (tid)
+ ret = virAsprintf(&proc, "/proc/%d/task/%d/sched", (int)pid,
(int)tid);
+ else
+ ret = virAsprintf(&proc, "/proc/%d/sched", (int)pid);
+ if (ret < 0)
+ goto cleanup;
+
+ /* The file is not guaranteed to exist (needs CONFIG_SCHED_DEBUG) */
+ if (access(proc, R_OK) < 0)
+ return 0;
+
+ if (virFileReadAll(proc, (1<<16), &data) < 0)
+ goto cleanup;
+
+ lines = virStringSplit(data, "\n", 0);
+ if (!lines)
+ goto cleanup;
+
+ for (i = 0; lines[i] != NULL; i++) {
+ const char *line = lines[i];
+
+ /* Needs CONFIG_SCHEDSTATS. The second check
+ * is the old name the kernel used in past */
+ if (STRPREFIX(line, "se.statistics.wait_sum") ||
+ STRPREFIX(line, "se.wait_sum")) {
+ line = strchr(line, ':');
+ if (!line) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Missing separate in sched info
'%s'"),
+ lines[i]);
+ goto cleanup;
+ }
+ line++;
+ while (*line == ' ') {
+ line++;
+ }
+
+ if (virStrToDouble(line, NULL, &val) < 0) {
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Unable to parse sched info value
'%s'"),
+ line);
+ goto cleanup;
+ }
+
+ *cpuWait = (unsigned long long)(val * 1000000);
+ break;
+ }
+ }
+
+ ret = 0;
+
+ cleanup:
+ VIR_FREE(data);
+ VIR_FREE(proc);
+ VIR_FREE(lines);
+ return ret;
+}
+
+
+static int
qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long *vm_rss,
pid_t pid, int tid)
{
@@ -1424,6 +1498,7 @@ qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long
*vm_rss,
static int
qemuDomainHelperGetVcpus(virDomainObjPtr vm,
virVcpuInfoPtr info,
+ unsigned long long *cpuwait,
int maxinfo,
unsigned char *cpumaps,
int maplen)
@@ -1476,6 +1551,11 @@ qemuDomainHelperGetVcpus(virDomainObjPtr vm,
virBitmapFree(map);
}
+ if (cpuwait) {
+ if (qemuGetSchedInfo(&(cpuwait[i]), vm->pid, vcpupid) < 0)
+ return -1;
+ }
+
ncpuinfo++;
}
@@ -5517,7 +5597,7 @@ qemuDomainGetVcpus(virDomainPtr dom,
goto cleanup;
}
- ret = qemuDomainHelperGetVcpus(vm, info, maxinfo, cpumaps, maplen);
+ ret = qemuDomainHelperGetVcpus(vm, info, NULL, maxinfo, cpumaps, maplen);
cleanup:
virDomainObjEndAPI(&vm);
@@ -19089,6 +19169,7 @@ qemuDomainGetStatsVcpu(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
int ret = -1;
char param_name[VIR_TYPED_PARAM_FIELD_LENGTH];
virVcpuInfoPtr cpuinfo = NULL;
+ unsigned long long *cpuwait = NULL;
if (virTypedParamsAddUInt(&record->params,
&record->nparams,
@@ -19104,10 +19185,12 @@ qemuDomainGetStatsVcpu(virQEMUDriverPtr driver
ATTRIBUTE_UNUSED,
virDomainDefGetVcpusMax(dom->def)) < 0)
return -1;
- if (VIR_ALLOC_N(cpuinfo, virDomainDefGetVcpus(dom->def)) < 0)
- return -1;
+ if (VIR_ALLOC_N(cpuinfo, virDomainDefGetVcpus(dom->def)) < 0 ||
+ VIR_ALLOC_N(cpuwait, virDomainDefGetVcpus(dom->def)) < 0)
+ goto cleanup;
- if (qemuDomainHelperGetVcpus(dom, cpuinfo, virDomainDefGetVcpus(dom->def),
+ if (qemuDomainHelperGetVcpus(dom, cpuinfo, cpuwait,
+ virDomainDefGetVcpus(dom->def),
NULL, 0) < 0) {
virResetLastError();
ret = 0; /* it's ok to be silent and go ahead */
@@ -19136,12 +19219,21 @@ qemuDomainGetStatsVcpu(virQEMUDriverPtr driver
ATTRIBUTE_UNUSED,
param_name,
cpuinfo[i].cpuTime) < 0)
goto cleanup;
+ snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH,
+ "vcpu.%zu.wait", i);
+ if (virTypedParamsAddULLong(&record->params,
+ &record->nparams,
+ maxparams,
+ param_name,
+ cpuwait[i]) < 0)
+ goto cleanup;
}
ret = 0;
cleanup:
VIR_FREE(cpuinfo);
+ VIR_FREE(cpuwait);
return ret;
}
--
2.5.0