Re: [PULL 09/12] migration: Use migration_transferred_bytes() to calculate rate_limit

[Fiona Ebner]

Am 23.05.23 um 14:31 schrieb Fiona Ebner:
> Am 18.05.23 um 19:13 schrieb Juan Quintela:
>> diff --git a/migration/migration-stats.c b/migration/migration-stats.c
>> index feec7d7369..97759a45f3 100644
>> --- a/migration/migration-stats.c
>> +++ b/migration/migration-stats.c
>> @@ -24,7 +24,9 @@ bool migration_rate_exceeded(QEMUFile *f)
>>          return true;
>>      }
>>  
>> -    uint64_t rate_limit_used = stat64_get(&mig_stats.rate_limit_used);
>> +    uint64_t rate_limit_start = stat64_get(&mig_stats.rate_limit_start);
>> +    uint64_t rate_limit_current = migration_transferred_bytes(f);
>> +    uint64_t rate_limit_used = rate_limit_current - rate_limit_start;
>>      uint64_t rate_limit_max = stat64_get(&mig_stats.rate_limit_max);
>>  
>>      if (rate_limit_max == RATE_LIMIT_DISABLED) {
> 
> Hi,
> just wanted to let you know that the call to
> migration_transferred_bytes(f) here can introduce a huge performance
> penalty when taking a snapshot. I ran into the issue when testing
> something else, with a single-disk snapshot. Without this call it takes
> about two seconds, with the call about two minutes.
> 
> 

Unfortunately, the regression is still in current master and v8.1-rc1.
Did the v2 [0] of the series never make it?

[0]: https://lists.nongnu.org/archive/html/qemu-devel/2023-05/msg07708.html

Best Regards,
Fiona