[libvirt] [PATCH v2 01/21] cgroup: Clean up virCgroupGetPercpuStats
Use 'ret' for return variable name, clarify use of 'param_idx' and avoid
unnecessary 'success' label. No functional changes. Also document the
function.
---
Notes:
V2:
- Fixed mistake in the refactor that would return incorrect error values (Found by
Jan)
- Added comment explaining the terriblenes of the function (Requested by John)
src/util/vircgroup.c | 64 +++++++++++++++++++++++++++++++++++-----------------
1 file changed, 43 insertions(+), 21 deletions(-)
diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index 9b56e27..da0df7a 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -3189,6 +3189,26 @@ virCgroupGetPercpuVcpuSum(virCgroupPtr group,
}
+/**
+ * virCgroupGetPercpuStats:
+ * @cgroup: cgroup data structure
+ * @params: typed parameter array where data is returned
+ * @nparams: cardinality of @params
+ * @start_cpu: offset of physical CPU to get data for
+ * @ncpus: number of physical CPUs to get data for
+ * @nvcpupids: number of vCPU threads for a domain (actual number of vcpus)
+ *
+ * This function is the worker that retrieves data in the appropriate format
+ * for the terribly designed 'virDomainGetCPUStats' API. Sharing semantics with
+ * the API, this function has two modes of operation depending on magic settings
+ * of the input arguments. Please refer to docs of 'virDomainGetCPUStats' for
+ * the usage patterns of the similarly named arguments.
+ *
+ * @nvcpupids determines the count of active vcpu threads for the vm. If the
+ * threads could not be detected the percpu data is skipped.
+ *
+ * Please DON'T use this function anywhere else.
+ */
int
virCgroupGetPercpuStats(virCgroupPtr group,
virTypedParameterPtr params,
@@ -3197,7 +3217,7 @@ virCgroupGetPercpuStats(virCgroupPtr group,
unsigned int ncpus,
unsigned int nvcpupids)
{
- int rv = -1;
+ int ret = -1;
size_t i;
int need_cpus, total_cpus;
char *pos;
@@ -3218,12 +3238,13 @@ virCgroupGetPercpuStats(virCgroupPtr group,
/* To parse account file, we need to know how many cpus are present. */
if (!(cpumap = nodeGetPresentCPUBitmap(NULL)))
- return rv;
+ return -1;
total_cpus = virBitmapSize(cpumap);
+ /* return total number of cpus */
if (ncpus == 0) {
- rv = total_cpus;
+ ret = total_cpus;
goto cleanup;
}
@@ -3261,34 +3282,35 @@ virCgroupGetPercpuStats(virCgroupPtr group,
goto cleanup;
}
- if (nvcpupids == 0 || param_idx + 1 >= nparams)
- goto success;
/* return percpu vcputime in index 1 */
- param_idx++;
+ param_idx = 1;
- if (VIR_ALLOC_N(sum_cpu_time, need_cpus) < 0)
- goto cleanup;
- if (virCgroupGetPercpuVcpuSum(group, nvcpupids, sum_cpu_time, need_cpus,
- cpumap) < 0)
- goto cleanup;
-
- for (i = start_cpu; i < need_cpus; i++) {
- if (virTypedParameterAssign(¶ms[(i - start_cpu) * nparams +
- param_idx],
- VIR_DOMAIN_CPU_STATS_VCPUTIME,
- VIR_TYPED_PARAM_ULLONG,
- sum_cpu_time[i]) < 0)
+ if (nvcpupids > 0 && param_idx < nparams) {
+ if (VIR_ALLOC_N(sum_cpu_time, need_cpus) < 0)
goto cleanup;
+ if (virCgroupGetPercpuVcpuSum(group, nvcpupids, sum_cpu_time, need_cpus,
+ cpumap) < 0)
+ goto cleanup;
+
+ for (i = start_cpu; i < need_cpus; i++) {
+ if (virTypedParameterAssign(¶ms[(i - start_cpu) * nparams +
+ param_idx],
+ VIR_DOMAIN_CPU_STATS_VCPUTIME,
+ VIR_TYPED_PARAM_ULLONG,
+ sum_cpu_time[i]) < 0)
+ goto cleanup;
+ }
+
+ param_idx++;
}
- success:
- rv = param_idx + 1;
+ ret = param_idx;
cleanup:
virBitmapFree(cpumap);
VIR_FREE(sum_cpu_time);
VIR_FREE(buf);
- return rv;
+ return ret;
}
--
2.6.2