Re: [PATCH v5 10/12] migration/dirtyrate: Implement calculate_dirtyrate() function

[David Edmondson <dme@dme.org>]

On Monday, 2020-08-24 at 17:14:38 +08, Chuan Zheng wrote:

> Implement calculate_dirtyrate() function.
>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
> ---
>  migration/dirtyrate.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index d1c0a78..9f52f5f 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -171,6 +171,21 @@ static void get_ramblock_dirty_info(RAMBlock *block,
>      strcpy(info->idstr, qemu_ram_get_idstr(block));
>  }
>  
> +static void free_ramblock_dirty_info(struct RamblockDirtyInfo *infos, int count)
> +{
> +    int i;
> +
> +    if (!infos) {
> +        return;
> +    }
> +
> +    for (i = 0; i < count; i++) {
> +        g_free(infos[i].sample_page_vfn);
> +        g_free(infos[i].hash_result);
> +    }
> +    g_free(infos);
> +}
> +
>  static struct RamblockDirtyInfo *
>  alloc_ramblock_dirty_info(int *block_index,
>                            struct RamblockDirtyInfo *block_dinfo)
> @@ -316,8 +331,34 @@ static int compare_page_hash_info(struct RamblockDirtyInfo *info,
>  
>  static void calculate_dirtyrate(struct DirtyRateConfig config)
>  {
> -    /* todo */
> -    return;
> +    struct RamblockDirtyInfo *block_dinfo = NULL;
> +    int block_index = 0;
> +    int64_t msec = 0;
> +    int64_t initial_time;
> +
> +    rcu_register_thread();
> +    reset_dirtyrate_stat();
> +    initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> +    rcu_read_lock();

Page dirtying that happens while acquiring the lock will not be
accounted for, but is within the time window. Could we store the time
after acquiring the lock?

> +    if (record_ramblock_hash_info(&block_dinfo, config, &block_index) < 0) {
> +        goto out;
> +    }
> +    rcu_read_unlock();
> +
> +    msec = config.sample_period_seconds * 1000;
> +    msec = set_sample_page_period(msec, initial_time);
> +
> +    rcu_read_lock();
> +    if (compare_page_hash_info(block_dinfo, block_index) < 0) {
> +        goto out;
> +    }
> +
> +    update_dirtyrate(msec);
> +
> +out:
> +    rcu_read_unlock();

Is it necessary to hold the lock across update_dirtyrate()?

> +    free_ramblock_dirty_info(block_dinfo, block_index + 1);
> +    rcu_unregister_thread();
>  }
>  
>  void *get_dirtyrate_thread(void *arg)
> -- 
> 1.8.3.1

dme.
-- 
There's someone in my head but it's not me.