Re: [Discuss-gnuradio] FIFO latency

Just want to throw this out there because it seems relevant:
http://gnuradio.org/cgit/jblum.git/tree/gruel/src/include/gruel/high_res_timer.h?h=wip/high_res_timer&id=71b911d28a391ad0c67540e3658a6680d7449e1f

On 05/28/2011 02:42 PM, Alexander Chemeris wrote:
> On Sat, May 28, 2011 at 22:06, Marcus D. Leech <mleech@ripnet.com> 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.
>

_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio