On Wed, 29 Mar 2017 23:12:00 +0200 Frederic Weisbecker <fweis...@gmail.com> wrote:
> On Wed, Mar 29, 2017 at 09:23:57AM -0400, Luiz Capitulino wrote: > > > > There are various reproducers actually. I started off with the simple > > loop above, then wrote the attach program and then wrote the one > > you're mentioning: > > > > http://people.redhat.com/~lcapitul/real-time/acct-bug.c > > > > All of them reproduce the issue 100% of the time for me. > > > #define _GNU_SOURCE > > #include <stdio.h> > > #include <unistd.h> > > #include <stdlib.h> > > #include <sched.h> > > #include <sys/types.h> > > > > static int move_to_cpu(int cpu) > > { > > cpu_set_t set; > > > > CPU_ZERO(&set); > > CPU_SET(cpu, &set); > > return sched_setaffinity(0, sizeof(set), &set); > > } > > > > static void loop(void) > > { > > for (;;) ; > > } > > > > static int fork_hog(int cpu) > > { > > int pid; > > > > pid = (int) fork(); > > if (pid == 0) { > > move_to_cpu(cpu); > > loop(); > > exit(0); > > } > > > > return pid; > > } > > > > int main(int argc, char *argv[]) > > { > > int i, pid, cpu, nr_procs; > > > > if (argc != 3) { > > printf("usage: hog < nr-procs > < CPU >\n"); > > exit(1); > > } > > > > cpu = atoi(argv[2]); > > nr_procs = atoi(argv[1]); > > > > for (i = 0; i < nr_procs; i++) { > > pid = fork_hog(cpu); > > fprintf(stderr, "created hog%d pid=%d\n", i, pid); > > } > > > > fprintf(stderr, "pausing...\n"); > > pause(); > > > > return 0; > > } > > I just tried both of these and none seem to show incorrect cputime :-/ > I'm wondering if that bug depends on some hardware. Are you running on x86? My CPU is: Intel(R) Xeon(R) CPU E5-2640 v3 @ 2.60GHz I wonder if this issue depends on the timer used by the hrtimer subsystem.
