static u32 measure_preemption(u32 target_ms) {
static volatile u32 v1, v2;
u64 st_t, en_t, st_c, en_c, real_delta, slice_delta;
s32 loop_repeats = 0;
st_t = get_cur_time_us();
st_c = get_cpu_usage_us();
repeat_loop:
v1 = CTEST_BUSY_CYCLES;
while (v1--) v2++;
sched_yield();
en_t = get_cur_time_us();
if (en_t - st_t < target_ms * 1000) {
loop_repeats++;
goto repeat_loop;
}
/* Let's see what percentage of this time we actually had a chance to
run, and how much time was spent in the penalty box. */
en_c = get_cpu_usage_us();
real_delta = (en_t - st_t) / 1000;
slice_delta = (en_c - st_c) / 1000;
return real_delta * 100 / slice_delta;
}
int main(int argc, char** argv) {
static volatile u32 v1, v2;
s32 loop_repeats = 0, util_perc;
u64 st_t, en_t, st_c, en_c, real_delta, slice_delta;
SAYF(cCYA "afl-gotcpu " cBRI VERSION cRST " (" __DATE__ " " __TIME__
") by <*****@*****.**>\n");
/* Run a busy loop for CTEST_TARGET_MS. */
ACTF("Measuring preemption rate (this will take %0.02f sec)...",
((double)CTEST_TARGET_MS) / 1000);
st_t = get_cur_time_us();
st_c = get_cpu_usage_us();
repeat_loop:
v1 = CTEST_BUSY_CYCLES;
while (v1--) v2++;
sched_yield();
en_t = get_cur_time_us();
if (en_t - st_t < CTEST_TARGET_MS * 1000) {
loop_repeats++;
goto repeat_loop;
}
/* Let's see what percentage of this time we actually had a chance to
run, and how much time was spent in the penalty box. */
en_c = get_cpu_usage_us();
real_delta = (en_t - st_t) / 1000;
slice_delta = (en_c - st_c) / 1000;
OKF("Busy loop hit %u times, real = %llu ms, slice = %llu ms.",
loop_repeats, real_delta, slice_delta);
util_perc = real_delta * 100 / slice_delta;
/* Deliver the final verdict. */
SAYF(cGRA "\n>>> ");
if (util_perc < 105) {
SAYF(cLGN "PASS: "******"You can probably run additional processes.");
} else if (util_perc < 130) {
SAYF(cYEL "CAUTION: " cRST "Your CPU may be somewhat overbooked (%u%%).",
util_perc);
} else {
SAYF(cLRD "FAIL: " cRST "Your CPU is overbooked (%u%%).", util_perc);
}
SAYF(cGRA " <<<" cRST "\n\n");
return (util_perc > 105) + (util_perc > 130);
}
