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Re: [Discuss-gnuradio] End-to-end delay question
From: |
Michael Dickens |
Subject: |
Re: [Discuss-gnuradio] End-to-end delay question |
Date: |
Tue, 22 May 2007 10:59:22 -0400 |
On May 22, 2007, at 12:28 AM, Eric Blossom wrote:
The priority is set to the midpoint of the FIFO range, not maximized.
My bad on the "maximized" ... but ... ummm ... no, not the midpoint
either the way it's written, if I understand the function calls
correctly. Here's the line:
int pri = (sched_get_priority_max (policy) -
sched_get_priority_min (policy)) / 2;
The midpoint would be (... + ...) / 2. ;)
I don't think we want to be creating new threads just to try
to set real time scheduling.
These changes are made to the current running thread, not to a new
thread, just like the code in "gr_realtime.cc". IMHO GNU Radio
already has enough threads, especially on OSX's implementation
because of Apple's weirdness of requiring separate threads for
callbacks on Audio and USB.
I strongly suspect that if a pthread
implementation supports pthread_attr_setschedpolicy with SCHED_RR or
SCHED_FIFO, then they will also implement sched_setscheduler with
SCHED_RR or SCHED_FIFO.
On OSX 10.4.9 (and, I would presume any 10.4.X):
sched_get_priority_max(), sched_get_priority_min (), SCHED_FIFO, and
"struct sched_param" [and "struct sched_param".sched_priority] are
defined in standard header files in /usr/include and seem to work as
required for modifying the scheduling priority and policy.
Strangely, the only part that's missing from headers is
sched_setscheduler() ... which gets divided and renamed to
pthread_attr_setschedpolicy() and pthread_attr_setschedparam().
I've tested out these pthread calls, and they work quite nicely w/o
needs for su or root execution. Shouldn't be difficult to create an
"#elif" condition in gr_realtime.cc for those with pthreads ... but
first the config m4 script for pthreads needs to work (at least on
OSX): config.h has "/* #undef HAVE_PTHREAD */" ... I will look into
these. - MLD
- [Discuss-gnuradio] End-to-end delay question, Steve Bunch, 2007/05/07
- Re: [Discuss-gnuradio] End-to-end delay question, Eric Blossom, 2007/05/07
- Re: [Discuss-gnuradio] End-to-end delay question, Bob McGwier, 2007/05/07
- Re: [Discuss-gnuradio] End-to-end delay question, Robert McGwier, 2007/05/07
- Re: [Discuss-gnuradio] End-to-end delay question, Steve Bunch, 2007/05/20
- Re: [Discuss-gnuradio] End-to-end delay question, Eric Blossom, 2007/05/21
- Re: [Discuss-gnuradio] End-to-end delay question, Michael Dickens, 2007/05/21
- Re: [Discuss-gnuradio] End-to-end delay question, Eric Blossom, 2007/05/22
- Re: [Discuss-gnuradio] End-to-end delay question,
Michael Dickens <=
- Re: [Discuss-gnuradio] End-to-end delay question, Eric Blossom, 2007/05/22
- Re: [Discuss-gnuradio] End-to-end delay question, Michael Dickens, 2007/05/23
- [Discuss-gnuradio] Reconfigurable OFDM using the USRP - it's possible, here's a video, Keith Nolan, 2007/05/23
- Re: [Discuss-gnuradio] End-to-end delay question, Eric Blossom, 2007/05/23
- Re: [Discuss-gnuradio] End-to-end delay question, Michael Dickens, 2007/05/24
- Re: [Discuss-gnuradio] End-to-end delay question, Eric A. Cottrell, 2007/05/22