Davide Libenzi wrote: > On Fri, 4 May 2007, Davi Arnaut wrote: > >> Hi, >> >> If multiple threads are parked on epoll_wait (on a single epoll fd) and >> events become available, epoll performs a wake up of all threads of the >> poll wait list, causing a thundering herd of processes trying to grab >> the eventpoll lock. >> >> This patch addresses this by using exclusive waiters (wake one). Once >> the exclusive thread finishes transferring it's events, a new thread >> is woken if there are more events available. >> >> Makes sense? > > Theorically, make sense. I said theorically because all the use > epoll_wait MT use cases I've heard of, use a single thread that does the > epoll_wait, and then dispatch to worker threads. So thundering herd is not > in the picture. OTOH, it does not hurt either.
A google search turns up a few users. It also addresses some complaints from Drepper. > But, that code is completely changed with the new single-pass epoll delivery > code that is in -mm. So, I'd either wait for that code to go in, or I > (or you, if you like) can make a patch against -mm. Fell free to update the patch for -mm and to include my signed-of-by. Thanks. -- Davi Arnaut - 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/