Re: [RFC PATCH 6/8] migration/dirtyrate: Implement get_sample_gap_period() and block_sample_gap_period()

[Dr. David Alan Gilbert]

* Chuan Zheng (zhengchuan@huawei.com) wrote:
> From: Zheng Chuan <zhengchuan@huawei.com>
> 
> Implement get_sample_gap_period() and block_sample_gap_period() to
> sleep specific time between sample actions.
> 
> Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhang <ann.zhuangyanying@huawei.com>
> ---
>  migration/dirtyrate.c | 28 ++++++++++++++++++++++++++++
>  migration/dirtyrate.h |  6 +++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index 7badc53..00abfa7 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -295,10 +295,38 @@ static void 
> set_dirty_rate_stage(CalculatingDirtyRateStage ratestage)
>      calculating_dirty_rate_stage = ratestage;
>  }
>  
> +static int64_t block_sample_gap_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);
> +    }

OK, so I think this is for sleeping in your own thread?
Since it's bounded at about 60s that's not too bad

> +    return msec;
> +}
> +
> +static int64_t get_sample_gap_period(struct dirtyrate_config config)
> +{
> +    int64_t msec;
> +
> +    msec = config.sample_period_seconds * 1000;
> +    if (msec <= MIN_FETCH_DIRTYRATE_TIME_MSEC || msec > 
> MAX_FETCH_DIRTYRATE_TIME_MSEC) {
> +        msec = DEFAULT_FETCH_DIRTYRATE_TIME_MSEC;
> +    }
> +    return msec;
> +}
> +
>  void *get_dirtyrate_thread(void *arg)
>  {
>      struct dirtyrate_config config = *(struct dirtyrate_config *)arg;
>      int64_t msec = 0;
> +
> +    /* max period is 60 seconds */
> +    msec = get_sample_gap_period(config);

(I'm not sure I understood where the config was set?)

>      set_dirty_rate_stage(CAL_DIRTY_RATE_ING);
>  
> diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
> index 4d9b3b8..5aef2d7 100644
> --- a/migration/dirtyrate.h
> +++ b/migration/dirtyrate.h
> @@ -14,12 +14,16 @@
>  #define QEMU_MIGRATION_DIRTYRATE_H
>  
>  /* take 256 pages per GB for cal dirty rate */
> -#define DIRTYRATE_DEFAULT_SAMPLE_PAGES    256
> +#define DIRTYRATE_DEFAULT_SAMPLE_PAGES  256

Not for this patch.

>  #define DIRTYRATE_SAMPLE_PAGE_SIZE      4096
>  #define DIRTYRATE_PAGE_SIZE_SHIFT       12
>  #define BLOCK_INFO_MAX_LEN              256
>  #define PAGE_SIZE_SHIFT                 20
>  
> +#define MIN_FETCH_DIRTYRATE_TIME_MSEC        0
> +#define MAX_FETCH_DIRTYRATE_TIME_MSEC        60000
> +#define DEFAULT_FETCH_DIRTYRATE_TIME_MSEC    1000
> +
>  struct dirtyrate_config {
>      uint64_t sample_pages_per_gigabytes;
>      int64_t sample_period_seconds;
> -- 
> 1.8.3.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK