Re: [PATCH 01/18] migration: Give one error if trying to set MULTIFD and XBZRLE

[Juan Quintela <quintela@redhat.com>]

Lukas Straub <lukasstraub2@web.de> wrote:
> On Tue, 13 Jun 2023 16:57:40 +0200
> Juan Quintela <quintela@redhat.com> wrote:
>
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>  migration/options.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/migration/options.c b/migration/options.c
>> index b62ab30cd5..c6674a4753 100644
>> --- a/migration/options.c
>> +++ b/migration/options.c
>> @@ -547,6 +547,13 @@ bool migrate_caps_check(bool *old_caps, bool *new_caps, Error **errp)
>>          }
>>      }
>>  
>> +    if (new_caps[MIGRATION_CAPABILITY_MULTIFD]) {
>> +        if (new_caps[MIGRATION_CAPABILITY_XBZRLE]) {
>> +            error_setg(errp, "Multifd is not compatible with xbzrle");
>> +            return false;
>> +        }
>> +    }
>> +
>>      return true;
>>  }
>>  
>
> Hmm, I think supporting xbzrle + multifd might be worthwhile as an
> alternative to xbzrle + compress.

Nack.

> I don't use it, but it should be easy to do by just letting xbzlre try
> to handle the page before multifd.

My idea here is to implement xbzrle as we implement zlib/zstd on
multifd.  Just go from there.

> There shouldn't be any incompatibilities other than that, as long as
> xbzlre sees the pages before multifd and the zero-page case is still
> handled the old way.

The way that I say is going to be easier and probably also faster.

Later, Juan.