papi_l2_dcw.c

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/* This code attempts to test the L2 Data Cache Writes      */
/* performance counter PAPI_L2_DCW              */

/* by Vince Weaver, vincent.weaver@maine.edu            */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "papi.h"
#include "papi_test.h"

#include "cache_helper.h"
#include "display_error.h"

#include "testcode.h"

#define NUM_RUNS    100

int main(int argc, char **argv) {

    int i;
    int eventset=PAPI_NULL;
    int num_runs=NUM_RUNS;
    long long high,low,average,expected;
    long long count,total;

    int retval;
    int l1_size,l2_size,l1_linesize,l2_linesize,l2_entries;
    int arraysize;
    int quiet,errors=0,warnings=0;

    double error;
    double *array;
    double aSumm = 0.0;

    quiet=tests_quiet(argc,argv);

    if (!quiet) {
        printf("Testing the PAPI_L2_DCW event\n");
    }

    /* Init the PAPI library */
    retval = PAPI_library_init(PAPI_VER_CURRENT);
    if (retval != PAPI_VER_CURRENT) {
        test_fail(__FILE__,__LINE__,"PAPI_library_init",retval);
    }

    retval=PAPI_create_eventset(&eventset);
    if (retval!=PAPI_OK) {
        test_fail( __FILE__, __LINE__, "PAPI_create_eventset", retval );
    }

    retval=PAPI_add_named_event(eventset,"PAPI_L2_DCW");
    if (retval!=PAPI_OK) {
        test_skip( __FILE__, __LINE__, "adding PAPI_L2_DCW", retval );
    }

    l1_size=get_cachesize(L1D_CACHE);
    l1_linesize=get_linesize(L1D_CACHE);
    l2_size=get_cachesize(L2_CACHE);
    l2_linesize=get_linesize(L2_CACHE);
    l2_entries=get_entries(L2_CACHE);

    if (!quiet) {
        printf("\tDetected %dk L1 DCache, %dB linesize\n",
            l1_size/1024,l1_linesize);
        printf("\tDetected %dk L2 DCache, %dB linesize, %d entries\n",
            l2_size/1024,l2_linesize,l2_entries);
    }

    arraysize=l2_size/sizeof(double);

    if (!quiet) {
        printf("\tAllocating %zu bytes of memory (%d doubles)\n",
            arraysize*sizeof(double),arraysize);
    }

    array=calloc(arraysize,sizeof(double));
    if (array==NULL) {
        test_fail(__FILE__,__LINE__,"Can't allocate memory",0);
    }

    /******************/
    /* Testing Writes */
    /******************/

    if (!quiet) {
        printf("\nWrite Test: Initializing an array of %d doubles:\n",
            arraysize);
        }

    high=0; low=0; total=0;

    for(i=0;i<num_runs;i++) {

        PAPI_reset(eventset);
        PAPI_start(eventset);

        cache_write_test(array,arraysize);

        retval=PAPI_stop(eventset,&count);

        if (retval!=PAPI_OK) {
            test_fail( __FILE__, __LINE__,
                "reading PAPI_L2_DCW", retval );
        }

        if (count>high) high=count;
        if ((low==0) || (count<low)) low=count;
        total+=count;
    }

    average=(total/num_runs);

    expected=arraysize/(l1_linesize/sizeof(double));

    if (!quiet) {
        printf("\tShould be roughly "
            "arraysize/L1_linesize/double_size (%d/%d/%zu): "
            "%lld\n\n",
            arraysize,l1_linesize,sizeof(double),
            expected);
    }

    error=display_error(average,high,low,expected,quiet);

    if ((error > 10.0) || (error<-10.0)) {
        if (!quiet) printf("Instruction count off by more than 1%%\n");
        errors++;
    }

    if (low<expected/10) {
        if (!quiet) printf("WARNING: Average OK but low value seems suspicious\n");
        warnings++;
    }

    if (!quiet) printf("\n");

    /******************/
    /* Testing Reads  */
    /******************/

    if (!quiet) {
        printf("\nRead Test: Summing an array of %d doubles:\n",
            arraysize);
        }

    high=0; low=0; total=0;

    for(i=0;i<num_runs;i++) {

        PAPI_reset(eventset);
        PAPI_start(eventset);

        aSumm+=cache_read_test(array,arraysize);

        retval=PAPI_stop(eventset,&count);

        if (retval!=PAPI_OK) {
            test_fail( __FILE__, __LINE__,
                "reading PAPI_L2_DCW", retval );
        }

        if (count>high) high=count;
        if ((low==0) || (count<low)) low=count;
        total+=count;
    }

    average=(total/num_runs);

    expected=(arraysize/(l1_linesize/sizeof(double)))/10;

    if (!quiet) {
        printf("\tShould be very low as we are measuring writes\n");
    }

    if (!quiet) {
        printf("Average writes: %lld\n",average);
    }



    if (average>expected) {
        if (!quiet) printf("ERROR: Write count unexpectedly high\n");
        errors++;
    }

    if (!quiet) {
        printf("\n");
    }

    /* FIXME: warn for now, as fail on broadwell and more recent */
    if (errors) {
        test_warn( __FILE__, __LINE__, "Error too high", 1 );
    }

    if (warnings) {
        test_warn(__FILE__, __LINE__, "Average results OK but some measurements low",1);
    }

    test_pass(__FILE__);

    return 0;
}