Where is the usleep source code?
Not the best subject line but I'm trying to figure out how the kernel does a usleep.
Specifically, I've been using a 3.0.4 kernel for a while and I get a fairly consistent usleep amount when compared to a hardware timer value (ARM EP9302). But I have been trying several newer kernel versions (and even a newer toolchain) and now usleep varies by as much as 50%. Yes, I know Linux isn't a real time OS but this is pretty awful. ITIMER_REAL is also severely impacted. When I use it to test the kernel Hz value, I'm seeing frequencies as low as 450 Hz and as high as 980 Hz when the kernel is configured for HZ=1000.