1kHz timer behavior on Cyclone V

Janet Schneider janetsc at fb.com
Wed Dec 14 02:32:10 UTC 2016

Hi everyone,

I ran more tests, and removed prints from the ISR unless they went out of bounds for what we are expecting.  The results were quite good - I did not see a latency greater than one microsecond on an hour run with a 1ms timer.  Thanks for the pointers!


From: users <users-bounces at rtems.org> on behalf of Thomas Doerfler (nt) <Thomas.Doerfler at imd-systems.de>
Sent: Thursday, December 8, 2016 10:58:45 PM
To: users at rtems.org
Subject: Re: 1kHz timer behavior on Cyclone V


it's even worse: since the transfer of one character (8 bits) requires a
leading startbit and a trailing stopbit (= total of 10 bits), you can
only print 11.52 characters per 1ms.

Am 09.12.2016 um 07:48 schrieb Sebastian Huber:
> Hello Janet,
> a printk() inside an ISR is quite bad. Lets assume it uses a serial
> line with 115200 bits per second, then you can print 14.4 characters
> per 1ms.

IMD Ingenieurbuero fuer Microcomputertechnik
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