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Re: [Qemu-devel] [PATCH v12 00/21] Multifd
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v12 00/21] Multifd |
Date: |
Thu, 3 May 2018 16:32:41 +0100 |
User-agent: |
Mutt/1.9.5 (2018-04-13) |
* Juan Quintela (address@hidden) wrote:
> 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.
I think most of the last few can be flattened into earlier patches;
I'd prefer it rather than having patches that add stuff and then they
get reworked/removed later.
I don't think it matters that the order of the last few doesn't work
until the end; since it didn't work at the beginning, it doesn't matter
until the end of the series.
Dave
> Later, Juan.
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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