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Re: [Qemu-devel] Tunneled Migration with Non-Shared Storage
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] Tunneled Migration with Non-Shared Storage |
Date: |
Wed, 19 Nov 2014 09:35:16 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Paolo Bonzini (address@hidden) wrote:
>
>
> On 18/11/2014 21:28, Dr. David Alan Gilbert wrote:
> > This seems odd, since as far as I know the tunneling code is quite separate
> > to the migration code; I thought the only thing that the migration
> > code sees different is the file descriptors it gets past.
> > (Having said that, again I don't know storage stuff, so if this
> > is a storage special there may be something there...)
>
> Tunnelled migration uses the old block-migration.c code. Non-tunnelled
> migration uses the NBD server and block/mirror.c.
OK, that explains that. Is that because the tunneling code can't
deal with tunneling the NBD server connection?
> The main problem with
> the old code is that uses a possibly unbounded amount of memory in
> mig_save_device_dirty and can have huge jitter if any serious workload
> is running in the guest.
So that's sending dirty blocks iteratively? Not that I can see
when the allocations get freed; but is the amount allocated there
related to total disk size (as Gary suggested) or to the amount
of dirty blocks?
Dave
>
> Paolo
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK