[PATCH v6 8/8] qemu_driver: Add calc_mode for dirtyrate statistics

[Michal Prívozník]

On 2/20/22 14:28, huangy81 at chinatelecom.cn wrote:
> From: Hyman Huang(黄勇) <huangy81 at chinatelecom.cn>
> 
> Add calc_mode for dirtyrate statistics retured by
> virsh domstats --dirtyrate api, also add vcpu dirtyrate
> if dirty-ring mode was used in last measurement.
> 
> Signed-off-by: Hyman Huang(黄勇) <huangy81 at chinatelecom.cn>
> ---
>  src/libvirt-domain.c         |  6 +++++
>  src/qemu/qemu_driver.c       | 22 +++++++++++++++---
>  src/qemu/qemu_monitor.h      | 10 +++++++++
>  src/qemu/qemu_monitor_json.c | 53 ++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 88 insertions(+), 3 deletions(-)
> 
> diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
> index 7be4e02..a197618 100644
> --- a/src/libvirt-domain.c
> +++ b/src/libvirt-domain.c
> @@ -11980,6 +11980,12 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
>   *     "dirtyrate.megabytes_per_second" - the calculated memory dirty rate in
>   *                                        MiB/s as long long. It is produced
>   *                                        only if the calc_status is measured.
> + *     "dirtyrate.calc_mode" - the calculation mode used last measurement, either
> + *                             of these 3 'page-sampling,dirty-bitmap,dirty-ring'
> + *                             values returned.
> + *     "dirtyrate.vcpu.<num>.megabytes_per_second" - the calculated memory dirty
> + *                                                   rate for a virtual cpu as
> + *                                                   unsigned long long.
>   *
>   * Note that entire stats groups or individual stat fields may be missing from
>   * the output in case they are not supported by the given hypervisor, are not
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 3297513..de2fdf7 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -18556,11 +18556,27 @@ qemuDomainGetStatsDirtyRate(virQEMUDriver *driver,
>                                  "dirtyrate.calc_period") < 0)
>          return -1;
>  
> -    if ((info.status == VIR_DOMAIN_DIRTYRATE_MEASURED) &&
> -        virTypedParamListAddLLong(params, info.dirtyRate,
> -                                  "dirtyrate.megabytes_per_second") < 0)
> +    if (virTypedParamListAddString(params,
> +                                   qemuMonitorDirtyRateCalcModeTypeToString(info.mode),
> +                                   "dirtyrate.calc_mode") < 0)
>          return -1;
>  
> +    if (info.status == VIR_DOMAIN_DIRTYRATE_MEASURED) {
> +        if (virTypedParamListAddLLong(params, info.dirtyRate,
> +                                      "dirtyrate.megabytes_per_second") < 0)
> +            return -1;
> +
> +        if (info.mode == QEMU_MONITOR_DIRTYRATE_CALC_MODE_DIRTY_RING) {
> +            int i;

Since info.nvcpus is size_t so must be i. We are not guaranteed that
size_t == int.

> +            for (i = 0; i < info.nvcpus; i++) {
> +                if (virTypedParamListAddULLong(params, info.rates[i].value,
> +                                               "dirtyrate.vcpu.%d.megabytes_per_second",
> +                                               info.rates[i].index) < 0)
> +                    return -1;
> +            }
> +        }
> +    }
> +
>      return 0;
>  }
>  
> diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
> index 053479b..2c0eed5 100644
> --- a/src/qemu/qemu_monitor.h
> +++ b/src/qemu/qemu_monitor.h
> @@ -1553,6 +1553,12 @@ qemuMonitorStartDirtyRateCalc(qemuMonitor *mon,
>                                int seconds,
>                                qemuMonitorDirtyRateCalcMode mode);
>  
> +typedef struct _qemuMonitorDirtyRateVcpu qemuMonitorDirtyRateVcpu;
> +struct _qemuMonitorDirtyRateVcpu {
> +    int index;                  /* virtual cpu index */

This makes our syntax-check report an error, because it thinks that
'index' is used to access an array (which must then be type of size_t
because that's the only type which is guaranteed to be big enough to
address individual bytes in memory). Let me change the name to 'idx'.

> +    unsigned long long value;   /* virtual cpu dirty page rate in MB/s */
> +};
> +
>  typedef struct _qemuMonitorDirtyRateInfo qemuMonitorDirtyRateInfo;
>  struct _qemuMonitorDirtyRateInfo {
>      int status;             /* the status of last dirtyrate calculation,
> @@ -1560,6 +1566,10 @@ struct _qemuMonitorDirtyRateInfo {
>      int calcTime;           /* the period of dirtyrate calculation */
>      long long startTime;    /* the start time of dirtyrate calculation */
>      long long dirtyRate;    /* the dirtyrate in MiB/s */
> +    qemuMonitorDirtyRateCalcMode mode;  /* calculation mode used in
> +                                           last measurement */
> +    size_t nvcpus;  /* number of virtual cpu */
> +    qemuMonitorDirtyRateVcpu *rates; /* array of dirty page rate */
>  };
>  
>  int
> diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
> index da9a4d9..a07f8c9 100644
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -8782,11 +8782,45 @@ VIR_ENUM_IMPL(qemuMonitorDirtyRateStatus,
>                "measured");
>  
>  static int
> +qemuMonitorJSONExtractVcpuDirtyRate(virJSONValue *data,
> +                                    qemuMonitorDirtyRateInfo *info)
> +{
> +    size_t nvcpus;
> +    int i;

Again, i has to be size_t.

> +
> +    nvcpus = virJSONValueArraySize(data);
> +    info->nvcpus = nvcpus;
> +    info->rates = g_new0(qemuMonitorDirtyRateVcpu, nvcpus);
> +
> +    for (i = 0; i < nvcpus; i++) {
> +        virJSONValue *entry = virJSONValueArrayGet(data, i);
> +        if (virJSONValueObjectGetNumberInt(entry, "id",
> +                                           &info->rates[i].index) < 0) {
> +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                           _("query-dirty-rate reply was missing 'id' data"));
> +            return -1;
> +        }
> +
> +        if (virJSONValueObjectGetNumberUlong(entry, "dirty-rate",
> +                                            &info->rates[i].value) < 0) {
> +            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                           _("query-dirty-rate reply was missing 'dirty-rate' data"));
> +            return -1;
> +        }
> +    }
> +
> +    return 0;
> +}

Michal