Re: [Qemu-devel] [PATCH v12 00/21] Multifd

[Juan Quintela]

Juan Quintela <address@hidden> wrote:
> Hi
>
>
> [v12]
>
> Big news, it is not RFC anymore, it works reliabely for me.
>
> Changes:
> - Locknig changed completely (several times)
> - We now send  all pages through the channels.  In a 2GB guest with 1 disk 
> and a network card, the amount of data send for RAM was 80KB.
> - This is not optimized yet, but it shouws clear improvements over precopy.  
> testing over localhost networking I can guet:
>   - 2 VCPUs guest
>   - 2GB RAM
>   - runn stress --vm 4 --vm 500GB (i.e. dirtying 2GB or RAM each second)
>
>   - Total time: precopy ~50seconds, multifd  around 11seconds
>   - Bandwidth usage is around 273MB/s vs 71MB/s on the same hardware
>
> This is very preleminary testing, will send more numbers when I got them.  
> But looks promissing.
>
> Things that will be improved later:
> - Initial synchronization is too slow (around 1s)
> - We synchronize all threads after each RAM section, we can move to only
>   synchronize them after we have done a bitmap syncrhronization
> - We can improve bitmap walking (but that is independent of multifd)

I forgot to put there that on the last 4 patches, I have not been able
to split them in a way that:
- is logical for review
- works for multifd tests in all versions

So, I ended trynig to get the "logical" viewe, and it works after the
last patch.  Why is that?
- Before I am able to transmit data, I need to be able to
  end/synchronize the different channels
- To finish channels in case of error, I just close the channels
  But I can't opet then yet.

I have to think if I can come with a simpler way to split it, but you
can also consider that the  last 3-4 patches are a single one.

Later, Juan.