I evaluated latency of a FIFO (actually an ordinary pipe, but the kernel
mechanisms are identical), and measured 30usecs average on my
1.2GHz AMD Phenom system with plenty 'o memory.
I sent timestamps across the FIFO (struct timeval), and the reader
grabbed the local time of day, and computed the difference. There’s
a fair amount of uncertainty on the reader due to gettimeofday() call
overhead. But 30usec on a wimpy CPU is certainly comfortably
Shirleys Bay Radio Astronomy Consortium