On Fri, 2010-08-20 at 10:25 -0400, Herrera-Bendezu, Luis wrote: > >-----Original Message----- > >From: Jan Kiszka [mailto:[email protected]] > >Sent: Friday, August 20, 2010 10:09 AM > >To: Philippe Gerum > >Cc: Herrera-Bendezu, Luis; [email protected] > >Subject: Re: RTDM task blocks when connecting gdb to realtime task > > > > > >Philippe Gerum wrote: > >> On Fri, 2010-08-20 at 15:58 +0200, Jan Kiszka wrote: > >>> Philippe Gerum wrote: > >>>>> However, terminating gdb and restarting app outside gdb > >>>>> does make RTDM task resume execution. Before, the driver had to be > >>>>> reloaded. > >>>>> > >>>>> So gdb appears to be causing timer to block even if no breakpoint is > >>>>> set, > >>>>> probably signals? > >>>>> > >>>> There is no reason for that. Sending "continue" to gdb is expected to > >>>> unblock the timers, until the code is single-stepped again (e.g. after > >>>> ^C or any breakpoint). > >>> gdb silently intercepts a traced program for various reasons, e.g. > >>> thread creation or library loading. Even if no user breakpoint is set, > >>> the program may briefly be stopped nevertheless. If that happens > >>> frequently enough, and every stop can add latencies to running timers... > >> > >> We are talking about permanent freeze of timers, not transient (at least > >> this is what I got from the ongoing discussion). > > > >Yes, but what would happen if the interruption rate is higher than the > >timer delay? Wouldn't we effectively end up with a permanent freeze? > > > >Jan > > Tracing lock_/unlock_timers() calls shows that program is frequently > stopped.
That is expected. The application receives a substantial amount of SIGTRAP/SIGSTOP under gdb; what saves us is that this should never be continuous. > I had to disable notification mechanism to report secondary > mode switch on rt tasks, rt_task_set_mode(), to get aperiodic tasks > back to rt operation when gdb resumes rt task. > > Thanks, > Luis -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
