Re: [Qemu-devel] Block I/O outside the QEMU global mutex was "Re: [RFC PATCH 00/17] Support for multiple "AIO contexts""

[Paolo Bonzini]

Il 09/10/2012 17:02, Anthony Liguori ha scritto:
> We've discussed previously about having an additional layer on top of
> the block API.
> 
> One problem with the block API today is that it doesn't distinguish
> between device access and internal access.  I think this is an
> opportunity to introduce a device-only API.

And what API would libqblock use?  I don't think this is a good idea
unless we can prove performance problems.

> In the very short term, I can imagine an aio fastpath that was only
> implemented in terms of the device API.  We could have a slow path that
> acquired the BQL.

Not sure I follow.

> > 4. Unlocked event loop thread.  This is simlar to QEMU's iothread except it
> >    doesn't take the big lock.  In theory we could have several of these 
> > threads
> >    processing at the same time.  virtio-blk ioeventfd processing will be 
> > done
> >    in this thread.
> 
> I think we're reasonable close to being able to do this FWIW.

Yes, I'm resending this series with your comments addressed.  It strays
a bit between your territory (main-loop) and Kevin's, I'll let you two
sort it out.

Paolo