Re: [PATCH 0/3] epoll: Add epoll_pwait1 syscall

On Thu, 01/08 17:28, Andy Lutomirski wrote:

On Thu, Jan 8, 2015 at 5:25 PM, Fam Zheng [off-list ref] wrote:

quoted

On Thu, 01/08 09:57, Andy Lutomirski wrote:

quoted

I'd like to see a more ambitious change, since the timer isn't the
only problem like this.  Specifically, I'd like a syscall that does a
list of epoll-related things and then waits.  The list of things could
include, at least:

 - EPOLL_CTL_MOD actions: level-triggered epoll users are likely to
want to turn on and off their requests for events on a somewhat
regular basis.

This sounds good to me.

quoted

 - timerfd_settime actions: this allows a single syscall to wait and
adjust *both* monotonic and real-time wakeups.

I'm not sure, doesn't this break orthogonality between epoll and timerfd?

Yes.  It's not very elegant, and more elegant ideas are welcome.

What is the purpose of embedding timerfd operation here? Modifying timerfd
for each poll doesn't sound a common pattern to me.

quoted

quoted

Would this make sense?  It could look like:

int epoll_mod_and_pwait(int epfd,
  struct epoll_event *events, int maxevents,
  struct epoll_command *commands, int ncommands,
  const sigset_t *sigmask);

What about flags?

No room.  Maybe it should just be a struct for everything instead of
separate args.

Also no room for timeout. A single struct sounds the only way to go.

Fam