Re: [PATCH] poll: Avoid extra wakeups

[Andi Kleen <andi@firstfloor.org>]

Eric Dumazet <dada1@cosmosbay.com> writes:
>
> When scheduled, thread does a full scan of all polled fds and
> can sleep again, because nothing is really available. If number
> of fds is large, this cause significant load.

I wonder if the key could be used for more state. For example if you
two processes are in recvmsg() on a socket and there's only a single
packet incoming we only need to wake up the first waiter.  Could that
be done with keys too?

> This patch makes select()/poll() aware of keyed wakeups and
> useless wakeups are avoided. This reduces number of context
> switches by about 50% on some setups, and work performed
> by sofirq handlers.

I'm late, but: very cool patch too.

Acked-by: Andi Kleen <ak@linux.intel.com>

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.