| /** |
| * @file |
| * This test burns some CPU cycles in user space and kernel space in order to |
| * get some non-zero values returned by times(2). |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| # include "config.h" |
| #endif |
| |
| #include <sched.h> |
| #include <stdio.h> |
| #include <time.h> |
| #include <unistd.h> |
| |
| #include <sys/syscall.h> |
| #include <sys/times.h> |
| #include <sys/wait.h> |
| |
| enum { |
| NUM_USER_ITERS = 1000000, |
| PARENT_CPUTIME_LIMIT_NSEC = 200000000, |
| CHILD_CPUTIME_LIMIT_NSEC = 300000000 |
| }; |
| |
| int |
| main (void) |
| { |
| struct timespec ts; |
| volatile int dummy; |
| int i; |
| |
| pid_t pid = fork(); |
| |
| if (pid < 0) |
| return 77; |
| |
| const long cputime_limit = |
| pid ? PARENT_CPUTIME_LIMIT_NSEC : CHILD_CPUTIME_LIMIT_NSEC; |
| |
| /* Enjoying my user time */ |
| while (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == 0) { |
| if (ts.tv_sec || ts.tv_nsec >= cputime_limit) |
| break; |
| |
| for (i = 0; i < NUM_USER_ITERS; ++i) |
| ++dummy; |
| } |
| |
| /* Enjoying my system time */ |
| while (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == 0) { |
| if (ts.tv_sec || ts.tv_nsec >= cputime_limit * 2) |
| break; |
| |
| sched_yield(); |
| } |
| |
| if (pid == 0) { |
| return 0; |
| } else { |
| wait(NULL); |
| } |
| |
| struct tms tbuf; |
| unsigned long long llres; |
| |
| /* |
| * On systems where user's and kernel's long types are the same, |
| * prefer direct times syscall over libc's times function because |
| * the latter is more prone to return value truncation. |
| */ |
| #if !defined __NR_times \ |
| || defined LINUX_MIPSN32 \ |
| || defined __x86_64__ && defined __ILP32__ |
| clock_t res = times(&tbuf); |
| |
| if ((clock_t) -1 == res) |
| return 77; |
| if (sizeof(res) < sizeof(unsigned long long)) |
| llres = (unsigned long) res; |
| else |
| llres = res; |
| #else |
| long res = syscall(__NR_times, &tbuf); |
| |
| if (-1L == res) |
| return 77; |
| else |
| llres = (unsigned long) res; |
| #endif |
| |
| printf("times({tms_utime=%llu, tms_stime=%llu, ", |
| (unsigned long long) tbuf.tms_utime, |
| (unsigned long long) tbuf.tms_stime); |
| printf("tms_cutime=%llu, tms_cstime=%llu}) = %llu\n", |
| (unsigned long long) tbuf.tms_cutime, |
| (unsigned long long) tbuf.tms_cstime, |
| llres); |
| puts("+++ exited with 0 +++"); |
| |
| return 0; |
| } |