[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Qemu-devel] [Qemu-block] [PATCH 2/3] xen-bus: allow AioContext to be specified for each event channel
> -----Original Message----- [snip] > > > I wonder if the `'is_external' parameter of aio_set_fd_handler shoud be > > > `true' here, instead. That flag seems to be used when making a snapshot > > > of a blockdev, for example. > > > > > > That was introduced by: > > > dca21ef23ba48f6f1428c59f295a857e5dc203c8^..c07bc2c1658fffeee08eb46402b2f66d55b07586 > > > > > > What do you think? > > > > Interesting. I admit I was merely transcribing what qemu_set_fd_handler() > > passes without really > looking into the values. Looking at the arguments that virtio-blk passes to > aio_set_event_notifier() > though, and what 'is_external' means, it would appear that setting it to true > is probably the right > thing to do. Do you want me to send a v2 of the series or can you fix it up? > > Hi, > Handlers are invoked by the aio_poll() event loop. Some handlers are > considered "external" in the sense that they submit new I/O requests > from the guest or outside world. Others are considered "internal" in > the sense that they are part of the block layer and not an entry point > into the block layer. > > There are points where the block layer wants to run the event loop but > new requests must not be submitted. In this case aio_disable_external() > will be called so that "external" handlers are not processed. > > For example, see virtio's virtio_queue_aio_set_host_notifier_handler(). > This is the virtqueue kick ioeventfd and it shouldn't be processed when > aio_disable_external() has been called. > Thanks for the explanation Stefan. Xen event channels/shared rings should indeed be considered as external sources. Cheers, Paul _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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