Hi Yuta, Please read this documentation with more info about it:
https://cwiki.apache.org/confluence/display/NUTTX/Short+Time+Delays BR, Alan On 4/29/21, yuta <yutr...@gmail.com> wrote: > Brennan, > Thank you for your advice. > > I checked links you shared and > https://www.gnu.org/software/libc/manual/html_node/CPU-Time.html > I got elapsed time. Thank you. > > However I'm wondering why the elapsed time I got was not exactly the same I > expected to get. > I tried below. > > // ***** start > clock_t start, end; > double cpu_time_used; > > start = clock(); > usleep(1000000); // 1sec > end = clock(); > > cpu_time_used = ((double)(end - start)) / CLOCKS_PER_SEC; > > printf("CPU time used: %f sec\n", cpu_time_used); > // ***** end > > What I got is ... > "CPU time used: 1.010000 sec" (I expected to get 1.000000 sec) > > Do you have any idea? > > Yuta Ide > > On 2021/04/30 0:30, Brennan Ashton wrote: >> On Thu, Apr 29, 2021, 8:16 AM yuta <yutr...@gmail.com> wrote: >> >>> Hi all. >>> >>> I'm new to NuttX. >>> >>> I'm not sure if it's no problem me asking some personal question about >>> NuttX here. (please tell me if better place to ask.) >>> >>> by the way, I have made my app in apps/examples/<my app>. It's working >>> well. Now, I would like to measure elapsed time during processing a >>> program by put codes like below. >>> >> NuttX supports the POSIX time interfaces so you are looking for something >> like this. >> >> https://www.gnu.org/software/libc/manual/html_node/Calculating-Elapsed-Time.html >> >> >> There is also CPU time measurements, but NuttX does not treat this >> exactly >> correct as it is expected to give the amount of clock ticks the CPU has >> spent on a process. Instead with NuttX you get ticks since boot. >> >> https://www.gnu.org/software/libc/manual/html_node/Processor-And-CPU-Time.html >> >> --Brennan >> >
