some problems from using PAPI

Question

Have u ever used PAPI?

Because PAPI support the kernel version >2.6.32(perf-events), I choose it to test my code.

Why I only get the same number(result) no matter what event-code I chose,such as PAPI_TOT_INS,PAPI_BR_INS,etc..

#include <stdio.h>
#include "papi.h"
int main(){
int i,j,k;
int a[300][300];
int b[300][300];
int c[300][300];
for(i=0;i<300;i++){
    for(j=0;j<300;j++){
        a[i][j]=1;
        b[i][j]=2;
        c[i][j]=0;
    }
}

int Events[1]={PAPI_TOT_INS};//={PAPI_BR_INS,PAPI_BR_MSP};

long_long values[1];//values[0]=0;

PAPI_start_counters(Events,1);

for(i=0;i<300;i++){
    for(j=0;j<300;j++){
        for(k=0;k<300;k++){
            c[i][j]+=a[i][k]*b[k][j];
        }
    }
}
printf("r is %d\n",c[0][0]);

PAPI_read_counters(values,1);

printf("events is %lld\n",values[0]);

for(i=0;i<300;i++){
    for(j=0;j<300;j++){
        for(k=0;k<300;k++){
            a[i][j]+=b[i][k]*c[k][j];
        }
    }
}

PAPI_accum_counters(values,1);

printf("events is %lld\n",values[0]);

for(i=0;i<300;i++){
            for(j=0;j<300;j++){
                    for(k=0;k<300;k++){
                            a[i][j]+=b[i][k]*c[k][j];
                    }
            }
    }

PAPI_stop_counters(values,1);

printf("events is %lld\n",values[0]);

return 0;
}

My thinking:

1.My pc(uname -a): Linux xunzhang-virtual-machine 2.6.35-28-generic #49-Ubuntu SMP Tue Mar ... X86_64 GNU/Linux

how can I(command) see my kernel's support of perf-events? I just use the default conclusion that >2.6.32....

2.I just use my virtual machine in my MAC, does this effect??..

Say something to guide/help me. Thanks!!

Answer 1

AFAIK, High level PAPI calls do not call foe explicit initialization. I have the same problem as you have. If you've solved it, can you please let me know how?

Answer 2

You are not initializing PAPI. You should, before starting the counting, do an initialization and after counting a shutdown. You might want to read the files inside the ctests directory to see how it is done.