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Re: [Qemu-devel] [RFC 4/6] migration: move dirty bitmap sync to ram_addr
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From: |
Dr. David Alan Gilbert |
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Subject: |
Re: [Qemu-devel] [RFC 4/6] migration: move dirty bitmap sync to ram_addr.h |
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Date: |
Mon, 1 Dec 2014 14:49:24 +0000 |
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User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Stefan Hajnoczi (address@hidden) wrote:
> On Thu, Nov 27, 2014 at 04:29:06PM +0000, Dr. David Alan Gilbert wrote:
> > * Stefan Hajnoczi (address@hidden) wrote:
> > > The dirty memory bitmap is managed by ram_addr.h and copied to
> > > migration_bitmap[] periodically during live migration.
> > >
> > > Move the code to sync the bitmap to ram_addr.h where related code lives.
> >
> > Is this sync code going to need to gain a barrier (although I'm not quite
> > sure which) to ensure it's picked up all changes?
>
> gcc makes these operations a full barrier:
> https://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html
Ah yes; actually our docs/atomics.txt is a good reference - all
the operations you're using are in the sequentially consistent
half of that doc.
Dave
>
> Stefan
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK