nmi_watchdog.c File Reference

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Functions
static int	detect_nmi_watchdog (void)
int	main (int argc, char **argv)

Function Documentation

detect_nmi_watchdog()

static int detect_nmi_watchdog ( void  )

static

Definition at line 20 of file nmi_watchdog.c.

                                     {
 
    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;
}

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main()

int main	(	int	argc,
		char **	argv
	)

Definition at line 39 of file nmi_watchdog.c.

                                  {
 
    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;
}

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