From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
rth@redhat.com, qemu-devel@nongnu.org,
Juan Quintela <quintela@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [RFC 4/6] migration: move dirty bitmap sync to ram_addr.h
Date: Mon, 1 Dec 2014 14:49:24 +0000 [thread overview]
Message-ID: <20141201144924.GE2504@work-vm> (raw)
In-Reply-To: <20141201140140.GC6744@stefanha-thinkpad.redhat.com>
* Stefan Hajnoczi (stefanha@redhat.com) wrote:
> On Thu, Nov 27, 2014 at 04:29:06PM +0000, Dr. David Alan Gilbert wrote:
> > * Stefan Hajnoczi (stefanha@redhat.com) 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 / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2014-12-01 14:49 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-27 12:29 [Qemu-devel] [RFC 0/6] memory: make dirty_memory[] accesses atomic Stefan Hajnoczi
2014-11-27 12:29 ` [Qemu-devel] [RFC 1/6] bitmap: add atomic set functions Stefan Hajnoczi
2014-11-27 16:42 ` Paolo Bonzini
2014-12-01 13:52 ` Stefan Hajnoczi
2014-11-27 12:29 ` [Qemu-devel] [RFC 2/6] bitmap: add atomic test and clear Stefan Hajnoczi
2014-11-27 16:43 ` Paolo Bonzini
2014-12-01 13:53 ` Stefan Hajnoczi
2014-11-27 12:29 ` [Qemu-devel] [RFC 3/6] memory: use atomic ops for setting dirty memory bits Stefan Hajnoczi
2014-11-27 12:29 ` [Qemu-devel] [RFC 4/6] migration: move dirty bitmap sync to ram_addr.h Stefan Hajnoczi
2014-11-27 16:29 ` Dr. David Alan Gilbert
2014-12-01 14:01 ` Stefan Hajnoczi
2014-12-01 14:49 ` Dr. David Alan Gilbert [this message]
2014-11-27 12:29 ` [Qemu-devel] [RFC 5/6] memory: replace cpu_physical_memory_reset_dirty() with test-and-clear Stefan Hajnoczi
2014-11-27 12:29 ` [Qemu-devel] [RFC 6/6] memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic Stefan Hajnoczi
2014-11-27 13:21 ` [Qemu-devel] [RFC 0/6] memory: make dirty_memory[] accesses atomic Peter Maydell
2014-11-28 12:44 ` Stefan Hajnoczi
2015-03-23 11:09 ` Paolo Bonzini
2015-03-24 16:48 ` Stefan Hajnoczi
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