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

[Zheng Chuan]

On 2020/8/26 18:21, David Edmondson wrote:
> 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?
> 
Yes, it would be better.
will fix in V6.

>> +    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()?
> 
There is no need for that.
Will fix it in V6.

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