On Thu, May 17, 2012 at 03:56:48PM -0600, Eric Blake wrote:
> From: Hu Tao <hutao@xxxxxxxxxxxxxx>
>
> This involves setting the cpuacct cgroup to a per-vcpu granularity,
> as well as summing the each vcpu accounting into a common array.
> Now that we are reading more than one cgroup file, we double-check
> that cpus weren't hot-plugged between reads to invalidate our
> summing.
>
> Signed-off-by: Eric Blake <eblake@xxxxxxxxxx>
> ---
>
> diff from v4: rewrite qemu code to use fewer malloc calls, fix
> some logic bugs
>
> src/qemu/qemu_driver.c | 123 ++++++++++++++++++++++++++++++++++++++++++++----
> src/util/cgroup.c | 4 +-
> 2 files changed, 117 insertions(+), 10 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 0fd7de1..f6d0985 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -104,7 +104,7 @@
> #define QEMU_NB_NUMA_PARAM 2
>
> #define QEMU_NB_TOTAL_CPU_STAT_PARAM 3
> -#define QEMU_NB_PER_CPU_STAT_PARAM 1
> +#define QEMU_NB_PER_CPU_STAT_PARAM 2
>
> #if HAVE_LINUX_KVM_H
> # include <linux/kvm.h>
> @@ -12563,8 +12563,69 @@ qemuDomainGetTotalcpuStats(virCgroupPtr group,
> return nparams;
> }
>
> +/* This function gets the sums of cpu time consumed by all vcpus.
> + * For example, if there are 4 physical cpus, and 2 vcpus in a domain,
> + * then for each vcpu, the cpuacct.usage_percpu looks like this:
> + * t0 t1 t2 t3
> + * and we have 2 groups of such data:
> + * v\p 0 1 2 3
> + * 0 t00 t01 t02 t03
> + * 1 t10 t11 t12 t13
> + * for each pcpu, the sum is cpu time consumed by all vcpus.
> + * s0 = t00 + t10
> + * s1 = t01 + t11
> + * s2 = t02 + t12
> + * s3 = t03 + t13
> + */
> +static int
> +getSumVcpuPercpuStats(virCgroupPtr group,
> + unsigned int nvcpu,
> + unsigned long long *sum_cpu_time,
> + unsigned int num)
> +{
> + int ret = -1;
> + int i;
> + char *buf = NULL;
> + virCgroupPtr group_vcpu = NULL;
> +
> + for (i = 0; i < nvcpu; i++) {
> + char *pos;
> + unsigned long long tmp;
> + int j;
> +
> + if (virCgroupForVcpu(group, i, &group_vcpu, 0) < 0) {
> + qemuReportError(VIR_ERR_INTERNAL_ERROR,
> + _("error accessing cgroup cpuacct for vcpu"));
> + goto cleanup;
> + }
> +
> + if (virCgroupGetCpuacctPercpuUsage(group, &buf) < 0)
> + goto cleanup;
> +
> + pos = buf;
> + for (j = 0; j < num; j++) {
> + if (virStrToLong_ull(pos, &pos, 10, &tmp) < 0) {
> + qemuReportError(VIR_ERR_INTERNAL_ERROR,
> + _("cpuacct parse error"));
> + goto cleanup;
> + }
> + sum_cpu_time[j] += tmp;
> + }
> +
> + virCgroupFree(&group_vcpu);
> + VIR_FREE(buf);
> + }
> +
> + ret = 0;
> +cleanup:
> + virCgroupFree(&group_vcpu);
> + VIR_FREE(buf);
> + return ret;
> +}
> +
> static int
> qemuDomainGetPercpuStats(virDomainPtr domain,
> + virDomainObjPtr vm,
> virCgroupPtr group,
> virTypedParameterPtr params,
> unsigned int nparams,
> @@ -12572,20 +12633,24 @@ qemuDomainGetPercpuStats(virDomainPtr domain,
> unsigned int ncpus)
> {
> char *map = NULL;
> + char *map2 = NULL;
> int rv = -1;
> int i, max_id;
> char *pos;
> char *buf = NULL;
> + unsigned long long *sum_cpu_time = NULL;
> + unsigned long long *sum_cpu_pos;
> + unsigned int n = 0;
> + qemuDomainObjPrivatePtr priv = vm->privateData;
> virTypedParameterPtr ent;
> int param_idx;
> + unsigned long long cpu_time;
>
> /* return the number of supported params */
> if (nparams == 0 && ncpus != 0)
> - return QEMU_NB_PER_CPU_STAT_PARAM; /* only cpu_time is supported */
> + return QEMU_NB_PER_CPU_STAT_PARAM;
>
> - /* return percpu cputime in index 0 */
> - param_idx = 0;
> - /* to parse account file, we need "present" cpu map */
> + /* To parse account file, we need "present" cpu map. */
> map = nodeGetCPUmap(domain->conn, &max_id, "present");
> if (!map)
> return rv;
> @@ -12608,30 +12673,70 @@ qemuDomainGetPercpuStats(virDomainPtr domain,
> pos = buf;
> memset(params, 0, nparams * ncpus);
>
> + /* return percpu cputime in index 0 */
> + param_idx = 0;
> +
> if (max_id - start_cpu > ncpus - 1)
> max_id = start_cpu + ncpus - 1;
>
> for (i = 0; i <= max_id; i++) {
> - unsigned long long cpu_time;
> -
> if (!map[i]) {
> cpu_time = 0;
> } else if (virStrToLong_ull(pos, &pos, 10, &cpu_time) < 0) {
> qemuReportError(VIR_ERR_INTERNAL_ERROR,
> _("cpuacct parse error"));
> goto cleanup;
> + } else {
> + n++;
> }
> if (i < start_cpu)
> continue;
> - ent = ¶ms[ (i - start_cpu) * nparams + param_idx];
> + ent = ¶ms[(i - start_cpu) * nparams + param_idx];
> if (virTypedParameterAssign(ent, VIR_DOMAIN_CPU_STATS_CPUTIME,
> VIR_TYPED_PARAM_ULLONG, cpu_time) < 0)
> goto cleanup;
> }
> +
> + /* return percpu vcputime in index 1 */
> + if (++param_idx >= nparams) {
> + rv = nparams;
> + goto cleanup;
> + }
> +
> + if (VIR_ALLOC_N(sum_cpu_time, n) < 0) {
> + virReportOOMError();
> + goto cleanup;
> + }
> + if (getSumVcpuPercpuStats(group, priv->nvcpupids, sum_cpu_time, n) < 0)
> + goto cleanup;
> +
> + /* Check that the mapping of online cpus didn't change mid-parse. */
> + map2 = nodeGetCPUmap(domain->conn, &max_id, "present");
> + if (!map2 || memcmp(map, map2, VIR_DOMAIN_CPUMASK_LEN) != 0)
> + goto cleanup;
> +
> + sum_cpu_pos = sum_cpu_time;
> + for (i = 0; i <= max_id; i++) {
> + if (!map[i])
> + cpu_time = 0;
> + else
> + cpu_time = *(sum_cpu_pos++);
> + if (i < start_cpu)
> + continue;
> + if (virTypedParameterAssign(¶ms[(i - start_cpu) * nparams +
> + param_idx],
> + VIR_DOMAIN_CPU_STATS_VCPUTIME,
> + VIR_TYPED_PARAM_ULLONG,
> + cpu_time) < 0)
> + goto cleanup;
> + }
> +
> rv = param_idx + 1;
> cleanup:
> + VIR_FREE(sum_cpu_time);
> VIR_FREE(buf);
> VIR_FREE(map);
> + VIR_FREE(map2);
> return rv;
> }
>
> @@ -12683,7 +12788,7 @@ qemuDomainGetCPUStats(virDomainPtr domain,
> if (start_cpu == -1)
> ret = qemuDomainGetTotalcpuStats(group, params, nparams);
> else
> - ret = qemuDomainGetPercpuStats(domain, group, params, nparams,
> + ret = qemuDomainGetPercpuStats(domain, vm, group, params, nparams,
> start_cpu, ncpus);
> cleanup:
> virCgroupFree(&group);
> diff --git a/src/util/cgroup.c b/src/util/cgroup.c
> index ad49bc2..5b32881 100644
> --- a/src/util/cgroup.c
> +++ b/src/util/cgroup.c
> @@ -530,7 +530,9 @@ static int virCgroupMakeGroup(virCgroupPtr parent, virCgroupPtr group,
> continue;
>
> /* We need to control cpu bandwidth for each vcpu now */
> - if ((flags & VIR_CGROUP_VCPU) && (i != VIR_CGROUP_CONTROLLER_CPU)) {
> + if ((flags & VIR_CGROUP_VCPU) &&
> + (i != VIR_CGROUP_CONTROLLER_CPU &&
> + i != VIR_CGROUP_CONTROLLER_CPUACCT)) {
> /* treat it as unmounted and we can use virCgroupAddTask */
> VIR_FREE(group->controllers[i].mountPoint);
> continue;
> --
> 1.7.7.6
ACK.
--
Thanks,
Hu Tao
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