Re: [Discuss-gnuradio] FIFO latency

[Alexander Chemeris]

On Sat, May 28, 2011 at 22:06, Marcus D. Leech <address@hidden> wrote:
> 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
>  below 1msec.

gettimeofday() is a fast function. But if you want real high-fidelity
- read CPU clock counter. Just make sure your app runs on a one
selected core.

Could you post your app and raw results? I'm interested in
min/mean/max values and distribution graphs. Because max values do
play role when playing with real-time.

-- 
Regards,
Alexander Chemeris.