Davide Libenzi wrote: > On Thu, 23 Apr 2009, Gregory Haskins wrote: > > >> This allows synchronous notifications to register with the eventfd >> infrastructure. Unlike traditional vfs based eventfd readers, notifiees >> do not implictly clear the counter on reception. However, the clearing >> is primarily important to allowing threads to block waiting for events >> anyway, so its an acceptable trade-off since blocking doesn't apply to >> notifiers. >> > > Do you really need to add a notifier? Eventfd already has a wait queue, > and we support callback-based wakeups, so is there any reason we shouldn't > use those and rely on the already existing wakeups? > Well, IIUC the issue is that a wait queue implies that you are in fact waiting...which we may not. :) The target in this particular application with kvm-irqfd is a vcpu context, which *may* be sleeping in something like a HLT, but it also could be in a number of other states such as non-root (guest) mode, it could be running in the kernel, it could be up in userspace, etc. That said: I am not married to the concept that this has to be a notifier callback, but I do want to be able to meet the target application. So if there is some way to do that within the existing wait-queue contstruct, I am open to suggestions. Thanks Davide, -Greg > > > - Davide > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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