[v5,06/10] hmp: add basic "info stats" implementation

From: Mark Kanda <mark.kanda@oracle.com>

Add an HMP command to retrieve statistics collected at run-time.
The command will retrieve and print either all VM-level statistics,
or all vCPU-level statistics for the currently selected CPU.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hmp-commands-info.hx  |  13 +++
 include/monitor/hmp.h |   1 +
 monitor/hmp-cmds.c    | 190 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 204 insertions(+)

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> From: Mark Kanda <mark.kanda@oracle.com>
> 
> Add an HMP command to retrieve statistics collected at run-time.
> The command will retrieve and print either all VM-level statistics,
> or all vCPU-level statistics for the currently selected CPU.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  hmp-commands-info.hx  |  13 +++
>  include/monitor/hmp.h |   1 +
>  monitor/hmp-cmds.c    | 190 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 204 insertions(+)
> 
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index 834bed089e..28757768f7 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -894,3 +894,16 @@ SRST
>    ``info via``
>      Show guest mos6522 VIA devices.
>  ERST
> +
> +    {
> +        .name       = "stats",
> +        .args_type  = "target:s",
> +        .params     = "target",
> +        .help       = "show statistics; target is either vm or vcpu",
> +        .cmd        = hmp_info_stats,
> +    },
> +
> +SRST
> +  ``stats``
> +    Show runtime-collected statistics
> +ERST
> diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
> index 96d014826a..2e89a97bd6 100644
> --- a/include/monitor/hmp.h
> +++ b/include/monitor/hmp.h
> @@ -133,5 +133,6 @@ void hmp_info_dirty_rate(Monitor *mon, const QDict *qdict);
>  void hmp_calc_dirty_rate(Monitor *mon, const QDict *qdict);
>  void hmp_human_readable_text_helper(Monitor *mon,
>                                      HumanReadableText *(*qmp_handler)(Error **));
> +void hmp_info_stats(Monitor *mon, const QDict *qdict);
>  
>  #endif
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 622c783c32..55b83c0a3a 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -40,6 +40,7 @@
>  #include "qapi/qapi-commands-pci.h"
>  #include "qapi/qapi-commands-rocker.h"
>  #include "qapi/qapi-commands-run-state.h"
> +#include "qapi/qapi-commands-stats.h"
>  #include "qapi/qapi-commands-tpm.h"
>  #include "qapi/qapi-commands-ui.h"
>  #include "qapi/qapi-visit-net.h"
> @@ -52,6 +53,7 @@
>  #include "ui/console.h"
>  #include "qemu/cutils.h"
>  #include "qemu/error-report.h"
> +#include "hw/core/cpu.h"
>  #include "hw/intc/intc.h"
>  #include "migration/snapshot.h"
>  #include "migration/misc.h"
> @@ -2239,3 +2241,191 @@ void hmp_info_memory_size_summary(Monitor *mon, const QDict *qdict)
>      }
>      hmp_handle_error(mon, err);
>  }
> +
> +static void print_stats_schema_value(Monitor *mon, StatsSchemaValue *value)
> +{
> +    const char *unit = NULL;
> +    monitor_printf(mon, "    %s (%s%s", value->name, StatsType_str(value->type),
> +                   value->has_unit || value->exponent ? ", " : "");
> +
> +    if (value->has_unit) {
> +        if (value->unit == STATS_UNIT_SECONDS) {
> +            unit = "s";
> +        } else if (value->unit == STATS_UNIT_BYTES) {
> +            unit = "B";
> +        }
> +    }
> +
> +    if (unit && value->base == 10 &&
> +        value->exponent >= -9 && value->exponent <= 0 &&
> +        value->exponent % 3 == 0) {
> +        monitor_printf(mon, "%s", si_prefix(value->exponent));
> +    } else if (unit && value->base == 2 &&
> +               value->exponent >= 0 && value->exponent <= 40 &&
> +               value->exponent % 10 == 0) {
> +
> +        monitor_printf(mon, "%s", iec_binary_prefix(value->exponent));

OK that's better; but it's a shame the limits don't come from something
shared; iec_binary_prefix goes upto 60 and si_prefix goes way below -9

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> +    } else if (value->exponent) {
> +        /* Use exponential notation and write the unit's English name */
> +        monitor_printf(mon, "* %d^%d%s",
> +                       value->base, value->exponent,
> +                       value->has_unit ? " " : "");
> +        unit = NULL;
> +    }
> +
> +    if (value->has_unit) {
> +        monitor_printf(mon, "%s", unit ? unit : StatsUnit_str(value->unit));
> +    }
> +
> +    /* Print bucket size for linear histograms */
> +    if (value->type == STATS_TYPE_LINEAR_HISTOGRAM && value->has_bucket_size) {
> +        monitor_printf(mon, ", bucket size=%d", value->bucket_size);
> +    }
> +    monitor_printf(mon, ")");
> +}
> +
> +static StatsSchemaValueList *find_schema_value_list(
> +    StatsSchemaList *list, StatsProvider provider,
> +    StatsTarget target)
> +{
> +    StatsSchemaList *node;
> +
> +    for (node = list; node; node = node->next) {
> +        if (node->value->provider == provider &&
> +            node->value->target == target) {
> +            return node->value->stats;
> +        }
> +    }
> +    return NULL;
> +}
> +
> +static void print_stats_results(Monitor *mon, StatsTarget target,
> +                                StatsResult *result,
> +                                StatsSchemaList *schema)
> +{
> +    /* Find provider schema */
> +    StatsSchemaValueList *schema_value_list =
> +        find_schema_value_list(schema, result->provider, target);
> +    StatsList *stats_list;
> +
> +    if (!schema_value_list) {
> +        monitor_printf(mon, "failed to find schema list for %s\n",
> +                       StatsProvider_str(result->provider));
> +        return;
> +    }
> +
> +    monitor_printf(mon, "provider: %s\n",
> +                   StatsProvider_str(result->provider));
> +
> +    for (stats_list = result->stats; stats_list;
> +             stats_list = stats_list->next,
> +             schema_value_list = schema_value_list->next) {
> +
> +        Stats *stats = stats_list->value;
> +        StatsValue *stats_value = stats->value;
> +        StatsSchemaValue *schema_value = schema_value_list->value;
> +
> +        /* Find schema entry */
> +        while (!g_str_equal(stats->name, schema_value->name)) {
> +            if (!schema_value_list->next) {
> +                monitor_printf(mon, "failed to find schema entry for %s\n",
> +                               stats->name);
> +                return;
> +            }
> +            schema_value_list = schema_value_list->next;
> +            schema_value = schema_value_list->value;
> +        }
> +
> +        print_stats_schema_value(mon, schema_value);
> +
> +        if (stats_value->type == QTYPE_QNUM) {
> +            monitor_printf(mon, ": %" PRId64 "\n", stats_value->u.scalar);
> +        } else if (stats_value->type == QTYPE_QLIST) {
> +            uint64List *list;
> +            int i;
> +
> +            monitor_printf(mon, ": ");
> +            for (list = stats_value->u.list, i = 1;
> +                 list;
> +                 list = list->next, i++) {
> +                monitor_printf(mon, "[%d]=%" PRId64 " ", i, list->value);
> +            }
> +            monitor_printf(mon, "\n");
> +        }
> +    }
> +}
> +
> +/* Create the StatsFilter that is needed for an "info stats" invocation.  */
> +static StatsFilter *stats_filter(StatsTarget target, int cpu_index)
> +{
> +    StatsFilter *filter = g_malloc0(sizeof(*filter));
> +
> +    filter->target = target;
> +    switch (target) {
> +    case STATS_TARGET_VM:
> +        break;
> +    case STATS_TARGET_VCPU:
> +    {
> +        strList *vcpu_list = NULL;
> +        CPUState *cpu = qemu_get_cpu(cpu_index);
> +        char *canonical_path = object_get_canonical_path(OBJECT(cpu));
> +
> +        QAPI_LIST_PREPEND(vcpu_list, canonical_path);
> +        filter->u.vcpu.has_vcpus = true;
> +        filter->u.vcpu.vcpus = vcpu_list;
> +        break;
> +    }
> +    default:
> +        break;
> +    }
> +    return filter;
> +}
> +
> +void hmp_info_stats(Monitor *mon, const QDict *qdict)
> +{
> +    const char *target_str = qdict_get_str(qdict, "target");
> +    StatsTarget target;
> +    Error *err = NULL;
> +    g_autoptr(StatsSchemaList) schema = NULL;
> +    g_autoptr(StatsResultList) stats = NULL;
> +    g_autoptr(StatsFilter) filter = NULL;
> +    StatsResultList *entry;
> +
> +    target = qapi_enum_parse(&StatsTarget_lookup, target_str, -1, &err);
> +    if (err) {
> +        monitor_printf(mon, "invalid stats target %s\n", target_str);
> +        goto exit_no_print;
> +    }
> +
> +    schema = qmp_query_stats_schemas(&err);
> +    if (err) {
> +        goto exit;
> +    }
> +
> +    switch (target) {
> +    case STATS_TARGET_VM:
> +        filter = stats_filter(target, -1);
> +        break;
> +    case STATS_TARGET_VCPU: {}
> +        int cpu_index = monitor_get_cpu_index(mon);
> +        filter = stats_filter(target, cpu_index);
> +        break;
> +    default:
> +        abort();
> +    }
> +
> +    stats = qmp_query_stats(filter, &err);
> +    if (err) {
> +        goto exit;
> +    }
> +    for (entry = stats; entry; entry = entry->next) {
> +        print_stats_results(mon, target, entry->value, schema);
> +    }
> +
> +exit:
> +    if (err) {
> +        monitor_printf(mon, "%s\n", error_get_pretty(err));
> +    }
> +exit_no_print:
> +    error_free(err);
> +}
> -- 
> 2.36.1
> 
>

On 6/7/22 20:35, Dr. David Alan Gilbert wrote:
>> +        monitor_printf(mon, "%s", iec_binary_prefix(value->exponent));
> OK that's better; but it's a shame the limits don't come from something
> shared; iec_binary_prefix goes upto 60 and si_prefix goes way below -9
> 
> Reviewed-by: Dr. David Alan Gilbert<dgilbert@redhat.com>
> 

I can remove the limits altogether, and consider it a bug of the 
provider if they're not respected, but it's a bit ugly to have an 
assertion failure in that case.

Paolo

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> On 6/7/22 20:35, Dr. David Alan Gilbert wrote:
> > > +        monitor_printf(mon, "%s", iec_binary_prefix(value->exponent));
> > OK that's better; but it's a shame the limits don't come from something
> > shared; iec_binary_prefix goes upto 60 and si_prefix goes way below -9
> > 
> > Reviewed-by: Dr. David Alan Gilbert<dgilbert@redhat.com>
> > 
> 
> I can remove the limits altogether, and consider it a bug of the provider if
> they're not respected, but it's a bit ugly to have an assertion failure in
> that case.

[I just noticed si_prefix is declared to take 'unsigned int' which is
probably wrong)

Why don't you change the si_prefix/iec_binary_prefix to return NULL
rather than asserting, then we end up with something like:

   exponentstr = NULL;
   if (unit && value->base == 10) {
       exponentstr = si_prefix(value->exponent);
   } else if (unit && value->base == 2) {
       exponentstr = iec_binary_prefix(value->exponent);
   }
   if (exponentstr) {
       monitor_printf(mon, "%s", exponentstr);
   } else if (value->exponent) {

Dave

> Paolo

>