Hi, This v4 is the follow-up to v3 at: https://lore.kernel.org/linux-fsdevel/20250527090836.1290532-1-namcao@xxxxxxxxxxxxx/ which resolves a priority inversion problem. The v3 patch was merged, but then got reverted due to regression. The direction of v3 was wrong in the first place. It changed the eventpoll's event list to be lockless, making the code harder to read. I stared at the patch again, but still couldn't figure out what the bug is. The performance numbers were indeed impressive with lockless, but the numbers are from a benchmark, which is unclear whether it really reflects real workload. This v4 takes a completely different approach: it converts the rwlock to spinlock. Unfortunately, unlike rwlock, spinlock does not allow concurrent readers. This patch therefore reduces the performance numbers. I have some optimization tricks to reduce spinlock contention and bring the numbers back. But Linus appeared and declared that epoll's performance shouldn't be the priority. So I decided not to post those optimization patches. For those who are curious, the optimization patches are at: git@xxxxxxxxxx:covanam/linux.git epoll_optimize be warned that they have not been well-tested. The regression with v3 turned me into paranoid mode now. So I made this v4 as obvious as I can. Nam Cao (1): eventpoll: Replace rwlock with spinlock fs/eventpoll.c | 139 +++++++++---------------------------------------- 1 file changed, 26 insertions(+), 113 deletions(-) -- 2.39.5
