* Eric Wong ([email protected]) wrote: > Hi, I'm looking to reduce contention for the ep->lock spin lock in epoll. > > I came across wfcqueue in Userspace RCU and am wondering if there's any > reason (other that lack of developer time/users) it hasn't been adapted > for the Linux kernel. > > I'd be happy to do the work if it's suitable (and omit parts which > may not be, such as busy wait).
Hi Eric, I'm glad you're interested in our data structure! I actually have a port ready, I just lacked the time for thorough testing and also lacked users of the API at kernel-level. It looks like now would be a good time to send the patch your way as a RFC! > Using a mutex lock (while in process context) for dequeue works for > epoll. I mainly want a lock-free enqueue for ep_poll_callback since > that may be called in IRQ context. You'd get even better than this: wait-free enqueue, with a simple xchg and store. > > I suppose I can also use the llist LIFO in ep_poll_callback and > reverse that while in process context, too... Yeah, but that seems more expensive than just having the list in the right order already. ;) Patch incoming in a separate post, Thanks, Mathieu > > > ref: http://git.lttng.org/userspace-rcu.git -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
