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Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmap
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic |
Date: |
Fri, 3 Aug 2018 09:49:22 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
* Vladimir Sementsov-Ogievskiy (address@hidden) wrote:
> 03.08.2018 11:33, Dr. David Alan Gilbert wrote:
> > * Denis V. Lunev (address@hidden) wrote:
> > > On 08/02/2018 12:50 PM, Dr. David Alan Gilbert wrote:
> > > > * Denis V. Lunev (address@hidden) wrote:
> > > >
> > > >
> > > > > > I don't quite understand the last two paragraphs.
> > > > > we are thinking right now to eliminate delay on regular IO
> > > > > for migration. There is some thoughts and internal work in
> > > > > progress. That is why I am worrying.
> > > > What downtime are you typicaly seeing and what are you aiming for?
> > > >
> > > > It would be good if you could explain what you're planning to
> > > > fix there so we can get a feel for it nearer the start of it
> > > > rather than at the end of the reviewing!
> > > >
> > > > Dave
> > > The ultimate goal is to reliable reach 100 ms with ongoing IO and
> > > you are perfectly correct about reviewing :)
> > That would be neat.
> >
> > > Though the problem is that right now we are just trying to
> > > invent something suitable :(
> > OK, some brain-storm level ideas:
> >
> > a) Throttle the write bandwidth at later stages of migration
> > (I think that's been suggested before)
> > b) Switch to some active-sync like behaviour where the writes
> > are sent over the network as they happen to the destination
> > (mreitz has some prototype code for that type of behaviour
> > for postcopy)
> > c) Write the writes into a buffer that gets migrated over the
> > migration stream to get committed on the destination side.
> >
> > As I say, brainstorm level ideas only!
> >
> > Dave
>
> Do you say about bitmaps migration? With current approach (postcopy) there
> should not be problems with downtime, as data can be sent after target vm
> start
The ideas above were meant to suggest ways to reduce the downtime due to
*write data* not bitmaps.
Dave
> >
> > > Den
> > >
> > > > > > However, coming back to my question; it was really saying that
> > > > > > normal guest IO during the end of the migration will cause
> > > > > > a delay; I'm expecting that to be fairly unrelated to the size
> > > > > > of the disk; more to do with workload; so I guess in your case
> > > > > > the worry is the case of big large disks giving big large
> > > > > > bitmaps.
> > > > > exactly!
> > > > >
> > > > > Den
> > > > --
> > > > Dr. David Alan Gilbert / address@hidden / Manchester, UK
> > --
> > Dr. David Alan Gilbert / address@hidden / Manchester, UK
>
>
> --
> Best regards,
> Vladimir
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, (continued)
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Dr. David Alan Gilbert, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Dr. David Alan Gilbert, 2018/08/02
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/02
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Dr. David Alan Gilbert, 2018/08/02
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/02
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, John Snow, 2018/08/02
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Dr. David Alan Gilbert, 2018/08/03
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Vladimir Sementsov-Ogievskiy, 2018/08/03
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic,
Dr. David Alan Gilbert <=
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/03
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Dr. David Alan Gilbert, 2018/08/03
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, John Snow, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Denis V. Lunev, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, John Snow, 2018/08/01
- Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Vladimir Sementsov-Ogievskiy, 2018/08/02
Re: [Qemu-block] [Qemu-devel] [PATCH 4/6] dirty-bitmaps: clean-up bitmaps loading and migration logic, Vladimir Sementsov-Ogievskiy, 2018/08/01