Roman Penyaev <rpenyaev@xxxxxxx> wrote: > Hi all, > > The goal of this patch is to reduce contention of ep_poll_callback() which > can be called concurrently from different CPUs in case of high events > rates and many fds per epoll. Problem can be very well reproduced by > generating events (write to pipe or eventfd) from many threads, while > consumer thread does polling. In other words this patch increases the > bandwidth of events which can be delivered from sources to the poller by > adding poll items in a lockless way to the list. Hi Roman, I also tried to solve this problem many years ago with help of the well-tested-in-userspace wfcqueue from Mathieu's URCU. I was also looking to solve contention with parallel epoll_wait callers with this. AFAIK, it worked well; but needed the userspace tests from wfcqueue ported over to the kernel and more review. I didn't have enough computing power to show the real-world benefits or funding to continue: https://lore.kernel.org/lkml/?q=wfcqueue+d:..20130501 It might not be too much trouble for you to brush up the wait-free patches and test them against the rwlock implementation. (I only noticed this thread since I was catching up on some public-inbox work :>)
