On 29/07/2015 13:53, Fam Zheng wrote: >> > Yes, though I think you'd end up reverting patches 10 and 11 in the end. > We will add outer disable/enable pairs to prevent another threads's aio_poll > from sneaking in between bdrv_aio_poll calls, but we needn't obsolete > bdrv_aio_poll() because of that - it can be useful by itself. For example > bdrv_aio_cancel shouldn't look at ioeventfd, otherwise it could spin for too > long on high load. Does that make sense?
Did you mean bdrv_drain() (when it is not already surrounded by disable/enable pairs in the caller)? But yes, that makes sense. I'm not sure that it makes sense to disable/enable in places such as bdrv_pread. The caller's block, if any, should suffice. In this sense you'd end up reverting large parts of patch 10. Then you would have to see how many calls to bdrv_aio_poll are still there, and how many can be converted with no semantic change to aio_poll (e.g. there's no difference in qemu-img.c), and you'd end up reverting patches 9 and 11 too. But we can look at that later. Paolo
