Re: [PATCH v7 09/12] migration/dirtyrate: Implement set_sample_page_period() and get_sample_page_period()

[Li Qiang <liq3ea@gmail.com>]

Chuan Zheng <zhengchuan@huawei.com> 于2020年9月9日周三 下午10:15写道：
>
> Implement set_sample_page_period()/get_sample_page_period() to sleep
> specific time between sample actions.
>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Reviewed-by: David Edmondson <david.edmondson@oracle.com>
> ---
>  migration/dirtyrate.c | 24 ++++++++++++++++++++++++
>  migration/dirtyrate.h |  6 ++++++
>  2 files changed, 30 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index ae1959b..8a30261 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -27,6 +27,30 @@
>  static int CalculatingState = DIRTY_RATE_STATUS_UNSTARTED;
>  static struct DirtyRateStat DirtyStat;
>
> +static int64_t set_sample_page_period(int64_t msec, int64_t initial_time)
> +{
> +    int64_t current_time;
> +
> +    current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> +    if ((current_time - initial_time) >= msec) {
> +        msec = current_time - initial_time;
> +    } else {
> +        g_usleep((msec + initial_time - current_time) * 1000);
> +    }
> +
> +    return msec;
> +}
> +
> +static bool get_sample_page_period(int64_t sec)


This function name may confuse people the this will get the period.
But in fact you just check whether the 'period' is valid.
I think it is better to name it to be 'is_sample_period_valid' or
something meaningful.

Thanks,
Li Qiang

> +{
> +    if (sec < MIN_FETCH_DIRTYRATE_TIME_SEC ||
> +        sec > MAX_FETCH_DIRTYRATE_TIME_SEC) {
> +        return false;
> +    }
> +
> +    return true;
> +}
> +
>  static int dirtyrate_set_state(int *state, int old_state, int new_state)
>  {
>      assert(new_state < DIRTY_RATE_STATUS__MAX);
> diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
> index faaf9da..8f9bc80 100644
> --- a/migration/dirtyrate.h
> +++ b/migration/dirtyrate.h
> @@ -29,6 +29,12 @@
>   */
>  #define MIN_RAMBLOCK_SIZE                         128
>
> +/*
> + * Take 1s as minimum time for calculation duration
> + */
> +#define MIN_FETCH_DIRTYRATE_TIME_SEC              1
> +#define MAX_FETCH_DIRTYRATE_TIME_SEC              60
> +
>  struct DirtyRateConfig {
>      uint64_t sample_pages_per_gigabytes; /* sample pages per GB */
>      int64_t sample_period_seconds; /* time duration between two sampling */
> --
> 1.8.3.1
>
>