On March 19, 2015 4:06:08 AM CDT, Alexander Krutwig <alexander.krut...@embedded-brains.de> wrote: >Hello, > >currently I am working on the implementation of FreeBSD timecounters >into RTEMS as illustrated in Ticket #2271 of the developer's board >(https://devel.rtems.org/ticket/2271). >In the progress, I found out that the minimum RTEMS system clock >frequency should at least be 20Hz to guarantee a correct functionality. >Are there users that are troubled by this minimum system clock >frequency?
I have been recommending 1 ms as a good starting spot for a clock tick quantum for years. It is a pretty safe least common divisor. And it minimizes the 1/2 tick average error more than larger values. I think the default it 10 ms so this should not impact that. This shouldn't be a problem. Just add a test to confdefs.h if it is above that and a warning or error. And update the manual for the configuration parameter about the recommended range. FWIW I have worked on production systems with ticks of 250 ns with no issue. I tested a mpc5200 and got down to 20ns ticks before the tests wouldn't make forward progress. The isr overhead was too much. >Best regards, > >-- >-------------------------------------------- >embedded brains GmbH >Alexander Krutwig >Dornierstr. 4 >D-82178 Puchheim >Germany >email: alexander.krut...@embedded-brains.de >Phone: +49-89-18 94 741 - 17 >Fax: +49-89-18 94 741 - 09 >PGP: Public key available on request. > >Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG. > >_______________________________________________ >devel mailing list >devel@rtems.org >http://lists.rtems.org/mailman/listinfo/devel --joel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
