Re: Thread behaviour using pthread

Hi Dave,

Here is a small example of how I was setting thread attributes:

main (int argc, char **argv)

{

pthread_attr_t attr;

struct sched_param sched_prio;

pthread_t PthreadId;

int Pri, Policy, ThreadNum, scope = -1;

int ErrorCode;

pid_t Pid;

struct sched_param SchedParam, GetSchedParam;


Pid = getpid();

printf("\n Main process pid = %d", Pid);

pthread_attr_setinheritsched(&attr,PTHREAD_EXPLICIT_SCHED);

// Setting scheduling policy and priority

sched_prio.sched_priority = 10;


// set the task priority

pthread_attr_setschedparam( &attr, &sched_prio);

// set thread creation state

pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

// set thread policy

pthread_attr_setschedpolicy(&attr, SCHED_FIFO);

pthread_attr_getschedpolicy (&attr, &Policy);

pthread_attr_getscope (&attr, &scope);

if (Policy == SCHED_FIFO) {

printf ("\nPolicy = FIFO\n");

} else if (Policy == SCHED_RR) {

printf ("\nPolicy = RR\n");

} else if (Policy == SCHED_OTHER) {

printf ("\nPolicy = OTHER\n");

}

if (scope == PTHREAD_SCOPE_SYSTEM) {

printf("\n PTHREAD_SCOPE_SYSTEM\n");

} else if ( scope == PTHREAD_SCOPE_PROCESS ) {

printf ("\n PTHREAD_SCOPE_PROCESS\n");

}

// Start task

ThreadNum = 1;

// Initialize attributes for the new thread

pthread_attr_init(&attr);


// Start task

ThreadNum = 1;

ErrorCode = pthread_create(&PthreadId, &attr,

ThreadEntry1,

&ThreadNum );



"David Schwartz" <davids@xxxxxxxxxxxxx> wrote in message
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"Igor" <igor_k70@xxxxxxxxxxx> wrote in message
news:e01713$dnh$1@xxxxxxxxxxxxxxxxxxxxxxxxx

I have tried using pthread library on Linux (2.6 kernel) and found that
setting parameters in the attr structure
do not seem to change anything in the thread behaviour - changing sched
policy (RR, FIFO) or RT priority. So, it seems that any changes to attr
structure for a thread are transparent. The only way I could change the
behaviour is by using process level calls like sched_setscheduler etc.on
a
thread.

Is there anything I am missing?

Post minimal example code, you may be doing it wrong. It's not
particularly difficult, but there are a few gotchas.

DS




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