I am trying to increase the limit on open files for nginx. I've set cat /proc/sys/fs/file-max to 1000000, set worker_rlimit_nofile to 8388608 but I still keep getting errors like:

setrlimit(RLIMIT_NOFILE, 8388608) failed (1: Operation not permitted)
accept4() failed (24: Too many open files)

How do I increase the limit on open files for nginx?