Kernel events without kevents
Posted Mar 15, 2007 13:45 UTC (Thu) by pphaneuf
Parent article: Kernel events without kevents
On the other hand, the poll interfaces do not provide a way for applications to receive events without the need to call into the kernel - a feature which has been requested by some interested parties.
I keep being mystified by this, since there clearly need to be some synchronization between userspace and the kernel, which seems to be done with kevent_commit(), which is... a system call, that, uh, calls into the kernel.
Generality of kevent with regard to AIO and other event sources can be interesting, its possibly avoiding copies through mmapping the ring buffer between userspace and the kernel, is another possibly interesting, and while I happen to not be too convinced by either of these points, they have the merit of at least existing.
But unless I am nuts (which might be the case!), getting events from kevent requires calling into the kernel. Either someone explains to me how this is not the case, exactly, or people stop saying that.
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