Re: [Qemu-devel] [PATCH] blk: fix aio context loss on media change

[Kevin Wolf]

Am 15.03.2017 um 14:39 hat Paolo Bonzini geschrieben:
> On 15/03/2017 12:03, Kevin Wolf wrote:
> > But we discussed this earlier, and while I'm not completely sure any
> > more about the details, I seem to remeber that Paolo said something
> > along the lines that AioContext is going away anyway and building the
> > code for proper management would be wasted time.
> 
> AioContext is going to stay, but everybody will be able to send
> operations to a BB/BDS from any AioContext.  The BDS AioContext will
> only matter for network devices, since they have to attach the file
> descriptor handlers somewhere.  For files it won't matter at all because
> you can use multiple Linux AIO context or thread pools at the same time.

Should the iothread option then become a -blockdev option rather than a
-device one?

> There should be a policy on which BB sets AioContext on the BDS (e.g.
> only the device does it), but apart from that, it should not be an issue.

We don't know which BBs are going to be attached. We don't necessarily
have a device at all, or we could have two of them.

Though maybe we should try to keep a BDS and its children in the same
AioContext anyway if that's possible? Will it make a difference?

Kevin