On 11/25/2013 10:58 AM, Chirayu Desai wrote: > > Sorry, I sent the last message to only Joel.
I MIGHT have eventually gotten to it. But am swamped. > ---------- Forwarded message ---------- > From: *Chirayu Desai* <chirayudes...@gmail.com > <mailto:chirayudes...@gmail.com>> > Date: 25 November 2013 15:30 > Subject: Re: Help with debugging a POSIX timing test. > To: Joel Sherrill <joel.sherr...@oarcorp.com > <mailto:joel.sherr...@oarcorp.com>> > > > > > > On 25 November 2013 00:35, Joel Sherrill <joel.sherr...@oarcorp.com > <mailto:joel.sherr...@oarcorp.com>> wrote: > > Now that I can see and run the code, a few things > jump out. > > + POSIX priorities -- lower numerically ==> more important > + You did &Thread_Id to calls after created. The & isn't > supposed to be there. > > + &policy should be the second argument to > pthread_getschedparam. > > This explains the ESRCH I was getting. Yep. And one of the compiler warnings as well. :) > + Pay attention to compiler warnings. :) > > Sorry for not doing so. No problem. This is a good example of how properly addressing the warning would have fixed the issue with no time in the debugger. Good programming practices try to keep you out of a debugger. :) > + Benchmark time is initialized IMMEDIATELY BEFORE the > single operation under test. We try to avoid including > anything. > > Got it. > > > I have attached a new version of init.c with comments > hacked in and changes. > > Thanks. > > > The big thing I tried to put in a comment block is that > the way this test is structured, it includes the hidden > start up time for the first time test_thread(0 runs. > I tried to write up notes on how to modify the test > to avoid that. > > I was unable to understand all of it. > From what I understood, POSIX_Init is called first, which > cals benchmark_pthread_setschedparam. > That creates a new thread, gets the priority and policy, and then > setschedparam is called > with the new (lowered) priority, which is what we want to test. pthread_create() creates and starts the thread. If it is more important than POSIX_Init(), it will immediately be switched to and run. But it isn't so it won't run until POSIX_Init() lowers its priority. > For convenience, I would add a helper routine like > this: > > void set_thread_priority( id, new_priority ) > > and call it. It will greatly simplify the code. > > Noted, I will do that after I get a better understanding of the code. Since you will be changing priority multiple times to switch back and forth, this will really help tighten the code. > I hope I didn't fall into the inverse > priority range trap in those instructions.... > > WARNING: POSIX priorities run INVERSE from the internal > priorities but in gdb if you print: > > p _Per_CPU_Information.per_cpu.executing->current_priority > > You will see the internal priority (NOT POSIX priority) > of the currently running thread. 1 is most important > and 255 is the IDLE task. > > I'm confused. > Per > http://www.rtems.org/onlinedocs/doxygen/cpukit/html/group__POSIX__PRIORITY.html#gada0c9a015d42fd545af7454f1ca0d098, > "RTEMS Core has priorities run in the opposite sense of the POSIX API." > So, for this task, lowering the POSIX priority is what we want, it is > the output I'm getting which confuses me > > Original priority: 2 > Lowered priority: 4 I am going to do this as a mix of internal and POSIX priorities Internal 255 is the lowest priority and illegal in POSIX. Internal 253 = POSIX_Init() at start (POSIX 2) see cpukit/posix/src/pthread.c for the default attributes Where you say lowered, it is actually becoming more important and moving to a numeric value with numbers above and below. At 2, there is little room below it. It is the next to lowest POSIX priority value. test_thread() is created at priority 2 also because the attributes are NULL. What you print as "Lowered priority" is actually the priority of test_thread() if I am reading things correctly. Hint: Make your set priority helper take (const char *, id, priority) and you can print the thread name in debug messages. :) When I break at test_thread(), the priority is POSIX=4, Internal=251 > So the numbers you pick are important to switch back and > forth between the tasks. > > I think the test is pretty close in spite of all that I > wrong. I stepped through the code attached and it is > doing the right thing EXCEPT including the thread hidden > start time. :) > > Benchmark programs are hard to get right but fun to write. > > Indeed :) Hope this helps. Stepping in gdb and printing the priority of the current thread helps. It will be the internal priority though. b POSIX_Init b test_thread and use p _Per_CPU_Information.per_cpu.executing->current_priority > > --joel > > On 11/24/2013 11:50 AM, Joel Sherrill wrote: > > Sorry to be lazy/stupid but how to I download just > > the diff to see what's going on? I am not that > > github literate. > > > > --joel > > > > On 11/24/2013 11:28 AM, Chirayu Desai wrote: > >> Hello everyone. > >> > >> I am Chirayu Desai, a high school student, currently participating in > >> Google Code-In 2013 > >> > >> I have currently working on the task [0], but I'm having some trouble > >> trying to get my code[1] to work. > >> > >> The task is to create a POSIX timing test psxtmthread05. > >> The test case is: pthread_setschedparam() - lower own priority. > >> I managed to write up something [2], but it doesn't work. > >> The GDB output is: > >> > >> (gdb) r > >> Starting program: > >> > > /home/cdesai/rtems/b-sis/sparc-rtems4.11/c/sis/testsuites/psxtmtests/psxtmthread05/psxtmthread05.exe > >> > >> > >> *** POSIX TIME TEST PSXTMTHREAD05 *** > >> getschedparam: 3 > >> Original priority: 5 > >> Lowered priority: 4 > >> setschedparam: 3 > >> pthread_setschedparam - lower own priority 2226 > >> *** END OF POSIX TIME TEST PSXTMTHREAD05 *** > >> [Inferior 1 (process 42000) exited normally] > >> > >> [0]: > >> > > http://www.google-melange.com/gci/task/view/google/gci2013/6383096106582016 > >> [1]: https://github.com/chirayudesai/rtems/tree/psxtmthread05 > >> [2]: > > https://github.com/chirayudesai/rtems/commit/890cebf084ca2a3815e3049a766276ddcdb0188a > >> > >> P.S. This is my first post to this list, so excuse me for any > mistakes. > >> > >> Regards, > >> Chirayu Desai > > > > > > > > > > -- > Joel Sherrill, Ph.D. Director of Research & Development > joel.sherr...@oarcorp.com On-Line Applications Research > Ask me about RTEMS: a free RTOS Huntsville AL 35805 > Support Available (256) 722-9985 > > > -- Joel Sherrill, Ph.D. Director of Research & Development joel.sherr...@oarcorp.com On-Line Applications Research Ask me about RTEMS: a free RTOS Huntsville AL 35805 Support Available (256) 722-9985 _______________________________________________ rtems-devel mailing list rtems-devel@rtems.org http://www.rtems.org/mailman/listinfo/rtems-devel
