Hi You probably need to look at https://wiki.linuxfoundation.org/realtime/documentation/howto/applications/start https://rt.wiki.kernel.org/index.php/Main_Page it not enough to just set policy and prio - you need to follow some additional rules while creating RT App. On 02/01/2018 09:52 PM, Journey Journey wrote: > Hi Dear All > > I had tested a program in order to calculate computing time in a > machine with 48 intel cpu cores. > > 1. when running ./test, it outputs like this: > MM: 324.039000 ms > MM: 324.052000 ms > MM: 324.079000 ms > MM: 324.042000 ms > MM: 324.060000 ms > MM: 324.052000 ms > MM: 324.026000 ms > MM: 324.040000 ms > MM: 324.075000 ms > MM: 324.011000 ms > MM: 324.072000 ms > > 2. running other programs, like sample code 2 > ./aa & > ./aa & > .... > about 30 times > > 3. ./test output changes: > MM: 354.601000 ms > MM: 322.289000 ms > MM: 322.250000 ms > MM: 322.348000 ms > MM: 354.700000 ms > MM: 322.556000 ms > MM: 354.834000 ms > MM: 354.816000 ms > MM: 354.777000 ms > MM: 354.812000 ms > MM: 322.451000 ms > MM: 322.507000 ms > MM: 322.473000 ms > > 4. For purpose to decrease computing cost time, I had tried: > (1) set test policy to SCHED_RR/SCHED_FIFO, and priority to 50/98 > chrt -f -p 98 5911 > (2) bind test to specific cpu > taskset -pc 4 5911 > (3) limit aa processes to other cpus > for i in `ps -ef |grep aa|awk '{print $2}'`; do echo $i; taskset -pc > 5-47 $i; done > > It still not working, the result is not good. > MM: 322.316000 ms > MM: 322.307000 ms > MM: 326.739000 ms > MM: 354.399000 ms > MM: 354.662000 ms > MM: 354.740000 ms > MM: 322.275000 ms > > 5. But when limit aa processes to a small cpuset, it works, > for i in `ps -ef |grep aa|awk '{print $2}'`; do echo $i; taskset -pc > 5-7 $i; done > > the result: > MM: 322.304000 ms > MM: 322.335000 ms > MM: 322.344000 ms > MM: 322.319000 ms > MM: 322.340000 ms > MM: 322.328000 ms > MM: 322.298000 ms > MM: 322.318000 ms > > > It's quite amazing why such low priority processes can affect realtime > process, please help me! > > > > Sample test code1: > > #include <stdio.h> > #include <sys/time.h> > > void calc() { > int c, d, k; > int m = 100000, q = 1, p = 1000; > int sum; > for (c = 0; c < m; c++) { > for (d = 0; d < q; d++) { > for (k = 0; k < p; k++) { > sum = c * m * d * q * p * k; > } > } > > } > } > > int main() { > struct timeval t1, t2; > double elapsedTime; > > while(1) { > gettimeofday(&t1, NULL); > calc(); > gettimeofday(&t2, NULL); > elapsedTime = (t2.tv_sec - t1.tv_sec) * 1000.0; // sec to ms > elapsedTime += (t2.tv_usec - t1.tv_usec) / 1000.0; // us to ms > printf("MM: %lf ms\n", elapsedTime); > sleep(1); > } > } > > > Sample Code 2: > > #include <stdio.h> > > int main() { > while(1) { > } > } > > Thanks~ > -- > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- regards, -grygorii -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
