Re: [PATCH 21/21] migration/multifd: Compute transferred bytes correctly

[Juan Quintela]

Peter Xu <peterx@redhat.com> wrote:
> On Mon, May 08, 2023 at 03:09:09PM +0200, Juan Quintela wrote:
>> In the past, we had to put the in the main thread all the operations
>> related with sizes due to qemu_file not beeing thread safe.  As now
>> all counters are atomic, we can update the counters just after the
>> do the write.  As an aditional bonus, we are able to use the right
>> value for the compression methods.  Right now we were assuming that
>> there were no compression at all.
>
> Maybe worth mention that initial packet is also accounted after this.

Ok.
>>  
>> +            stat64_add(&mig_stats.multifd_bytes, p->next_packet_size);
>> +            stat64_add(&mig_stats.transferred, p->next_packet_size);
>
> Two nits:
>
> Maybe merge the two so half atomic operations?

On my tree, to send after this got in:

77fdd3475c migration: Remove transferred atomic counter

O:-)

> Also maybe also worth having a inline helper for adding both multifd_bytes
> and transferred?

I am removing it.

After next set of packates:

rate limit is calulated as:

begining_period = migration_transferred_bytes();
...

bytes_this_period = migration_transferred_bytes() - begining_period;

transferred is calculated as:
- multifd_bytes + qemu_file_bytes;

So things get really simple.  As all counters are atomic, you do a
write and after the write to increse the write size to the qemu_file or
to the multifd_bytes.  And that is it.


> With/without that, all look good:
>
> Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks, Juan.