When we are sharing a wakeup source among multiple epoll fds, we end up with thundering herd wakeups, since there is currently no way to add to the wakeup source exclusively. This series introduces 2 new epoll flags, EPOLLEXCLUSIVE for adding to a wakeup source exclusively. And EPOLLROUNDROBIN which is to be used in conjunction to EPOLLEXCLUSIVE to evenly distribute the wakeups. This patch was originally motivated by a desire to improve wakeup balance and cpu usage for a listen socket() shared amongst multiple epoll fd sets.
See: http://lwn.net/Articles/632590/ for previous test program and testing resutls. Epoll manpage text: EPOLLEXCLUSIVE Provides exclusive wakeups when attaching multiple epoll fds to a shared wakeup source. Must be specified with an EPOLL_CTL_ADD operation. EPOLLROUNDROBIN Provides balancing for exclusive wakeups when attaching multiple epoll fds to a shared wakeup soruce. Depends on EPOLLEXCLUSIVE being set and must be specified with an EPOLL_CTL_ADD operation. Thanks, -Jason Jason Baron (2): sched/wait: add round robin wakeup mode epoll: introduce EPOLLEXCLUSIVE and EPOLLROUNDROBIN fs/eventpoll.c | 25 ++++++++++++++++++++----- include/linux/wait.h | 11 +++++++++++ include/uapi/linux/eventpoll.h | 6 ++++++ kernel/sched/wait.c | 10 ++++++++-- 4 files changed, 45 insertions(+), 7 deletions(-) -- 1.8.2.rc2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
