On Tue, 8 Jan 2008, Eric Dumazet wrote: > Changli Gao a écrit : > > Replace the epitem rbtree with a dynamic array to get the constant > > insertion/deletion/modification time of the file descriptors. Reuse the > > size argument of epoll_create, however the size must be smaller than the > > max file descriptor number: ether the resource limitation or the compiling > > time limitation. > > > > > Hum, you should read this : > > http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.7-rc3/2.6.7-rc3-mm2/broken-out/epoll-uses-rbtrees.patch > > > Your patch is a revert of this change, it probably wont be accepted. > > epoll_ctl() is scalable, since it's O(log2(N)) : With 1 millions files > descriptors, that means less than 20 nodes to lookup in the tree.
Indeed, and we aren't going back. > In what situation do you think epoll_ctl() performance is bad ? I'm sure you can cook up a microbench that only does epoll_ctl(), and with a good hash implementation you get better numbers. This is what I did before I changed to rbtree, and the numbers did not justify the code (the "size" in epoll_create() is just an hint, and that means you need to handle resizing - plus other things like locking up memory when the number of fds shrinks, and other stuff I don't even remember). - Davide
