/* If the NMI watchdog is enabled it will steal a performance counter.   */

/* There is a bug that if you try to use the maximum number of counters  */

/*   (not counting the stolen one) with a group leader, sys_perf_open()  */

/* will indicate success, as will starting the count, but you will fail  */

/* at read time.                                                         */

/* This bug still exists in 3.x */

/* The perf NMI watchdog was not introduced until 2.6.34        */

/* This also triggers in the case of the schedulability bug      */

/* but since that was fixed in 2.6.34 then in theory there is    */

/* no overlap in the tests.                                      */

#include <stdio.h>

#include "papi.h"

#include "papi_test.h"

static int detect_nmi_watchdog(void) {

	int watchdog_detected=0,watchdog_value=0;

	FILE *fff;

	fff=fopen("/proc/sys/kernel/nmi_watchdog","r");

	if (fff!=NULL) {

		if (fscanf(fff,"%d",&watchdog_value)==1) {

			if (watchdog_value>0) watchdog_detected=1;

		}

		fclose(fff);

	}

	else {

		watchdog_detected=-1;

	}

	return watchdog_detected;

}

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

	int retval,watchdog_active=0;

	int quiet;

	/* Set TESTS_QUIET variable */

	quiet=tests_quiet( argc, argv );

	/* Init the PAPI library */

	retval = PAPI_library_init( PAPI_VER_CURRENT );

	if ( retval != PAPI_VER_CURRENT ) {

		test_fail( __FILE__, __LINE__, "PAPI_library_init", retval );

	}

	watchdog_active=detect_nmi_watchdog();

	if (watchdog_active<0) {

		test_skip( __FILE__, __LINE__,

			"nmi_watchdog file does not exist\n", 0);

	}

	if (watchdog_active) {

		if (!quiet) {

	printf("\nOn perf_event kernels with the nmi_watchdog enabled\n");

	printf("the watchdog steals an event, but the scheduability code\n");

	printf("is not notified.  Thus adding a full complement of events\n");

	printf("seems to pass, but then fails at read time.\n");

	printf("Because of this, PAPI has to do some slow workarounds.\n");

	printf("For best PAPI performance, you may wish to disable\n");

	printf("the watchdog by running (as root)\n");

	printf("\techo \"0\" > /proc/sys/kernel/nmi_watchdog\n\n");

		}

		test_warn( __FILE__, __LINE__,

			"NMI Watchdog Active, enabling slow workarounds", 0 );

	}

	test_pass( __FILE__ );

 	return 0;

}