On Thu, Jul 03, 2014 at 06:59:20PM +0200, Paolo Bonzini wrote: > In many cases, the call to event_notifier_set in aio_notify is unnecessary. > In particular, if we are executing aio_dispatch, or if aio_poll is not > blocking, we know that we will soon get to the next loop iteration (if > necessary); the thread that hosts the AioContext's event loop does not > need any nudging. > > The patch includes a Promela formal model that shows that this really > works and does not need any further complication such as generation > counts. It needs a memory barrier though. > > The generation counts are not needed because we only care of the state > of ctx->dispatching at the time the memory barrier happens. If > ctx->dispatching is one at the time the memory barrier happens, > the aio_notify is not needed even if it afterwards becomes zero. > > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > --- > It should work, but I think this is a bit too tricky for 2.1. > > aio-posix.c | 34 +++++++++++++++- > async.c | 13 +++++- > docs/aio_notify.promela | 104 > ++++++++++++++++++++++++++++++++++++++++++++++++ > include/block/aio.h | 9 +++++ > 4 files changed, 158 insertions(+), 2 deletions(-) > create mode 100644 docs/aio_notify.promela
I can test rbd and gluster. Thanks, applied to my block tree: https://github.com/stefanha/qemu/commits/block Stefan
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