On Sat, Mar 28, 2015 at 07:37:18AM +0100, Paolo Bonzini wrote: > bdrv_aio_* APIs can use coroutines to achieve asynchronicity. However, > the coroutine may terminate without having yielded back to the caller > (for example because of something that invokes a nested event loop, > or because the coroutine is doing nothing at all). In this case, > the bdrv_aio_* API must delay the completion to the next iteration > of the main loop, because bdrv_aio_* will never invoke the callback > before returning. > > This can be done with a bottom half, and indeed bdrv_aio_* is always > using one for simplicity. It is possible to gain some performance > (~3%) by avoiding this in the common case. A new field in the > BlockAIOCBCoroutine struct is set to true until the first time the > corotine has yielded to its creator, and completion goes through a > new function bdrv_co_complete. If the flag is false, bdrv_co_complete > invokes the callback immediately. If it is true, the caller will > notice that the coroutine has completed and schedule the bottom > half itself. > > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > --- > block.c | 43 ++++++++++++++++++++++++++++++++++--------- > 1 file changed, 34 insertions(+), 9 deletions(-)
Thanks, applied to my block-next tree: https://github.com/stefanha/qemu/commits/block-next Stefan
pgp37lrGeYypU.pgp
Description: PGP signature
