runtime: utilize EVFILT_USER more effectively
Re-work kqueue_event wakeup logic to use one-shot events. In an
event of waking up a wrong thread, simply re-post the event.
This saves close to 1 system call per wakeup on average, since
chances of non-blocking poller picking it up is pretty low.
Change-Id: I202d0d57a31d91ac5354ea075215f647c65790d3
GitHub-Last-Rev:
e707d4732683702bd2989f07230a2f34354c288b
GitHub-Pull-Request: golang/go#70408
Reviewed-on: https://go-review.googlesource.com/c/go/+/628975
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>