The timeout argument has an upper limit. Any values above that limit are treated the same as -1, i.e. to wait indefinitely. The limit is given by: #define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ) That is, the limit depends on the size of a long and the timer frequency. Assuming the a long is never smaller than 32 bits and HZ never larger than 1000, the worst case is 35 minutes. I think this should be mentioned under "BUGS". Although this is likely to be fixed in the future (http://lkml.org/lkml/2010/8/8/144), the problem exists in at least 2.6.14 - 2.6.35. I don't know if select(2) and poll(2) are affected.
I aplied the following patch: --- a/man2/epoll_wait.2 +++ b/man2/epoll_wait.2 @@ -198,6 +198,18 @@ If the new file descriptor becomes ready, it will cause the .BR epoll_wait () call to unblock. +.SH BUGS +In kernels before 2.6.37, a +.I timeout +value larger than approximately +.I LONG_MAX / HZ +milliseconds is treated as \-1 (i.e., infinity). +Thus, for example, on a system where the +.I sizeof(long) +is 4 and the kernel +.I HZ +value is 1000, +this means that timeouts greater than 35.79 minutes are treated as infinity. .SH "SEE ALSO" .BR epoll_create (2), .BR epoll_ctl (2),