Re: [PATCH v7 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function

[Li Qiang]

Chuan Zheng <zhengchuan@huawei.com> 于2020年9月9日周三 下午10:14写道：
>
> 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 | 62 
> +++++++++++++++++++++++++++++++++++++++++++++++++++
>  qapi/migration.json   | 50 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 112 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index 2f9ac34..e9e9e35 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -61,6 +61,24 @@ 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) {

Should we use atomic read 'CalculatingState'? The qmp thread maybe run
with the sampled thread.

> +        info->dirty_rate = dirty_rate;
> +    } else {
> +        info->dirty_rate = -1;
> +    }
> +
> +    info->status = CalculatingState;
> +    info->start_time = DirtyStat.start_time;
> +    info->calc_time = DirtyStat.calc_time;
> +
> +    return info;
> +}
> +


>  static void reset_dirtyrate_stat(void)
>  {
>      DirtyStat.total_dirty_samples = 0;
> @@ -331,6 +349,8 @@ static void calculate_dirtyrate(struct DirtyRateConfig 
> config)
>
>      msec = config.sample_period_seconds * 1000;
>      msec = set_sample_page_period(msec, initial_time);
> +    DirtyStat.start_time = initial_time / 1000;
> +    DirtyStat.calc_time = msec / 1000;
>
>      rcu_read_lock();
>      if (compare_page_hash_info(block_dinfo, block_index) < 0) {
> @@ -362,3 +382,45 @@ 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;
> +    int ret;
> +
> +    /*
> +     * If the dirty rate is already being measured, don't attempt to start.
> +     */
> +    if (CalculatingState == DIRTY_RATE_STATUS_MEASURING) {

atomic read?

> +        error_setg(errp, "the dirty rate is already being measured.");
> +        return;
> +    }
> +
> +    if (!get_sample_page_period(calc_time)) {
> +        error_setg(errp, "calc-time is out of range[%d, %d].",
> +                         MIN_FETCH_DIRTYRATE_TIME_SEC,
> +                         MAX_FETCH_DIRTYRATE_TIME_SEC);
> +        return;
> +    }
> +
> +    /*
> +     * Init calculation state as unstarted.
> +     */
> +    ret = dirtyrate_set_state(&CalculatingState, CalculatingState,
> +                              DIRTY_RATE_STATUS_UNSTARTED);
> +    if (ret == -1) {
> +        error_setg(errp, "init dirty rate calculation state failed.");
> +        return;
> +    }
> +
> +    config.sample_period_seconds = calc_time;
> +    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 061ff25..4b980a0 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1737,3 +1737,53 @@
>  ##
>  { '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'
> +#
> +# @start-time: start time in units of second for calculation
> +#
> +# @calc-time: time in units of second for sample dirty pages
> +#
> +# Since: 5.2
> +#
> +##
> +{ 'struct': 'DirtyRateInfo',
> +  'data': {'dirty-rate': 'int64',
> +           'status': 'DirtyRateStatus',
> +           'start-time': 'int64',
> +           'calc-time': 'int64'} }
> +
> +##
> +# @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": "calc-dirty-rate", "data": {"calc-time": 1} }
> +#
> +##
> +{ '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
>
>