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Re: [Qemu-devel] [RFC 10/29] migration: new property "x-postcopy-fast"
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC 10/29] migration: new property "x-postcopy-fast" |
Date: |
Tue, 1 Aug 2017 09:50:02 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Peter Xu (address@hidden) wrote:
> On Mon, Jul 31, 2017 at 07:52:24PM +0100, Dr. David Alan Gilbert wrote:
> > * Peter Xu (address@hidden) wrote:
> > > This provides a way to start postcopy ASAP when migration starts. To do
> > > this, we need both:
> > >
> > > -global migration.x-postcopy-ram=on \
> > > -global migration.x-postcopy-fast=on
> >
> > Can you explain why this is necessary? Both sides already know
> > they're doing a postcopy recovery don't they?
>
> What I wanted to do here is to provide a way to start postcopy at the
> very beginning (actually it'll possibly start postcopy at the first
> loop in migration_thread), instead of start postcopy until we trigger
> it using "migrate_start_postcopy" command.
>
> I used it for easier debugging (so I don't need to type
> "migrate_start_postcopy" every time when I trigger postcopy
> migration), meanwhile I think it can also be used when someone really
> want to start postcopy from the very beginning.
>
> Would such a new parameter makes sense?
Other than debugging, I don't think there's a real use for it; the
slight delay between starting migration and triggering postcopy has
very little cost.
Dave
>
> --
> Peter Xu
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [RFC 10/29] migration: new property "x-postcopy-fast",
Dr. David Alan Gilbert <=