Re: [RFC PATCH 0/3] epoll: read(),write(),ioctl() interface

From: Eric Wong
Date: Mon Feb 03 2014 - 17:02:16 EST


Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> >> On 02/02/2014 06:17 PM, Nathaniel Yazdani wrote:
> > So are you saying that those features you mentioned are specifically sought
> > after for the kernel? If so I'd like to take a crack at some of them,
> > may as well
> > get some use out of my new knowledge of epoll internals :)
>
> If by "sought after", you mean "is there at least one epoll user who
> wants them", then yes :)
>
> I think that EPOLLET and EPOLLONESHOT are giant hacks, and that what
> everyone really wants is the ability to very efficiently toggle events
> on and off. The ability to do it simultaneously and inexpensively
> with epoll_wait would make it happen.

Everybody using single-threaded epoll, you mean? I suppose there's
quite a few of those.

I've pondered an epoll_xchg syscall which would behave like *BSD kevent
to satisfy single-threaded users, but never got around to it. All my
epoll uses are multithreaded w/ oneshot nowadays, so xchg would only
save one syscall per thread.
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