Re: [PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function

[David Edmondson]

On Monday, 2020-08-24 at 17:14:39 +08, Chuan Zheng wrote:

> Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function which could be 
> called
>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> ---
>  migration/dirtyrate.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  qapi/migration.json   | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 89 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index 9f52f5f..08c46d3 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -62,6 +62,28 @@ static int dirtyrate_set_state(int *state, int old_state, 
> int new_state)
>      }
>  }
>  
> +static struct DirtyRateInfo *query_dirty_rate_info(void)
> +{
> +    int64_t dirty_rate = DirtyStat.dirty_rate;
> +    struct DirtyRateInfo *info = g_malloc0(sizeof(DirtyRateInfo));
> +
> +    if (CalculatingState == DIRTY_RATE_STATUS_MEASURED) {
> +        info->dirty_rate = dirty_rate;
> +    } else {
> +        info->dirty_rate = -1;
> +    }
> +
> +    info->status = CalculatingState;
> +    /*
> +     * Only support query once for each calculation,
> +     * reset as DIRTY_RATE_STATUS_UNSTARTED after query
> +     */
> +    (void)dirtyrate_set_state(&CalculatingState, CalculatingState,
> +                              DIRTY_RATE_STATUS_UNSTARTED);

Is there a reason for this restriction? Removing it would require
clarifying the state model, I suppose.

> +
> +    return info;
> +}
> +
>  static void reset_dirtyrate_stat(void)
>  {
>      DirtyStat.total_dirty_samples = 0;
> @@ -378,3 +400,26 @@ void *get_dirtyrate_thread(void *arg)
>                                DIRTY_RATE_STATUS_MEASURED);
>      return NULL;
>  }
> +
> +void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
> +{
> +    static struct DirtyRateConfig config;
> +    QemuThread thread;
> +
> +    /*
> +     * We don't begin calculating thread only when it's in calculating 
> status.

"If the dirty rate is already being measured, don't attempt to start."

> +     */
> +    if (CalculatingState == DIRTY_RATE_STATUS_MEASURING) {

Should this return an error to the caller?

> +        return;
> +    }
> +
> +    config.sample_period_seconds = get_sample_page_period(calc_time);

If the specified sample period is outside the min/max, should an error
be returned to the caller?

> +    config.sample_pages_per_gigabytes = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
> +    qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
> +                       (void *)&config, QEMU_THREAD_DETACHED);
> +}
> +
> +struct DirtyRateInfo *qmp_query_dirty_rate(Error **errp)
> +{
> +    return query_dirty_rate_info();
> +}
> diff --git a/qapi/migration.json b/qapi/migration.json
> index d640165..826bfd7 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1737,3 +1737,47 @@
>  ##
>  { 'enum': 'DirtyRateStatus',
>    'data': [ 'unstarted', 'measuring', 'measured'] }
> +
> +##
> +# @DirtyRateInfo:
> +#
> +# Information about current dirty page rate of vm.
> +#
> +# @dirty-rate: @dirtyrate describing the dirty page rate of vm
> +#          in units of MB/s.
> +#          If this field return '-1', it means querying is not
> +#          start or not complete.
> +#
> +# @status: status containing dirtyrate query status includes
> +#          'unstarted' or 'measuring' or 'measured'
> +#
> +# Since: 5.2
> +#
> +##
> +{ 'struct': 'DirtyRateInfo',
> +  'data': {'dirty-rate': 'int64',
> +           'status': 'DirtyRateStatus'} }
> +
> +##
> +# @calc-dirty-rate:
> +#
> +# start calculating dirty page rate for vm
> +#
> +# @calc-time: time in units of second for sample dirty pages
> +#
> +# Since: 5.2
> +#
> +# Example:
> +#   {"command": "cal-dirty-rate", "data": {"calc-time": 1} }

"cal-dirty-rate" -> "calc-dirty-rate".

> +#
> +##
> +{ 'command': 'calc-dirty-rate', 'data': {'calc-time': 'int64'} }
> +
> +##
> +# @query-dirty-rate:
> +#
> +# query dirty page rate in units of MB/s for vm
> +#
> +# Since: 5.2
> +##
> +{ 'command': 'query-dirty-rate', 'returns': 'DirtyRateInfo' }
> -- 
> 1.8.3.1

dme.
-- 
I'm going in the out door, I'm doing all right.