double experiment(qint64 len, int fdRef, int fdMiss)
{
std::vector<int> v(len);
std::vector<int> vRand(len);
int samples = 10;
double rate = 0.0;
for (int i = 0; i < samples; i++) {
long vRefI, vMissI, vRefF, vMissF;
int ret = 0;
write_linear(v);
write_random(vRand);
read_linear(v);
ret = read(fdRef, &vRefI, sizeof(vRefI));
ret = read(fdMiss, &vMissI, sizeof(vMissI));
read_random(v, vRand);
ret = read(fdRef, &vRefF, sizeof(vRefF));
ret = read(fdMiss, &vMissF, sizeof(vMissF));
vMissF -= vMissI;
vRefF -= vRefI;
double delta = (double)vMissF / vRefF;
qDebug() << "ret" << ret << " L1 Cache Accesses: "<< vRefF << " L1 Cache Misses: "<< vMissF <<" value " << delta;
rate += delta;
}
return rate / samples;
}
void write_random(std::vector<int> &v)
{
write_linear(v);
std::random_shuffle(v.begin(), v.end());
}
int do_experiment(const CounterTypeEnum::Type type)
{
perf_event_attr attr;
memset(&attr, 0, sizeof(attr));
attr.size = sizeof(attr);
/*
* General hardware counter
* IPC = instruction / cycles
* Miss ratio = references / misses
*/
switch (type) {
case CounterTypeEnum::INSTRUCTIONS:
attr.type = PERF_TYPE_HARDWARE;
attr.config = PERF_COUNT_HW_INSTRUCTIONS;
break;
case CounterTypeEnum::CYCLES:
attr.type = PERF_TYPE_HARDWARE;
attr.config = PERF_COUNT_HW_CPU_CYCLES;
break;
case CounterTypeEnum::L1_READ:
attr.type = PERF_TYPE_HW_CACHE;
attr.config = (PERF_COUNT_HW_CACHE_L1D) |
(PERF_COUNT_HW_CACHE_OP_READ << 8) |
(PERF_COUNT_HW_CACHE_RESULT_ACCESS << 16);
break;
case CounterTypeEnum::L1_MISSES:
attr.type = PERF_TYPE_HW_CACHE;
attr.config = (PERF_COUNT_HW_CACHE_L1D) |
(PERF_COUNT_HW_CACHE_OP_READ << 8) |
(PERF_COUNT_HW_CACHE_RESULT_MISS << 16);
break;
default:
qDebug() << "invalid counter selected";
return -1;
}
pid_t tid = gettid();
int fd = sys_perf_event_open(&attr, tid, -1, -1, 0);
int samples = 10;
long sum = 0;
int len = 1000;
std::vector<int> v(len);
std::vector<int> buf(1E6);
(void) buf;
for (int i = 0; i < samples; i++) {
long v1, v2;
int ret = 0;
// Read the counter value
ret = read(fd, &v1, sizeof(v1));
assert(ret > 0);
// do some work
write_linear(v);
// Read the counter value
ret = read(fd, &v2, sizeof(v2));
assert(ret > 0);
long delta = v2 - v1;
qDebug() << CounterTypeEnum::Names[type] << "value" << delta;
sum += delta;
}
qDebug() << CounterTypeEnum::Names[type] << " avg value" << sum / samples;
close(fd);
return 0;
}