Commit 7c6fee25 authored by Patryk Wlazlyn's avatar Patryk Wlazlyn Committed by Len Brown
Browse files

tools/power turbostat: Check for non-zero value when MSR probing 



For some MSRs, for example, the Platform Energy Counter (RAPL PSYS), it
is required to additionally check for a non-zero value to confirm that
it is present.

From Intel SDM vol. 4:

    Platform Energy Counter (R/O)
    This MSR is valid only if both platform vendor hardware
    implementation and BIOS enablement support it.
    This MSR will read 0 if not valid.

Signed-off-by: default avatarPatryk Wlazlyn <patryk.wlazlyn@linux.intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 1af5baed

tools/power/x86/turbostat/turbostat.c

+7 −3
Original line number Diff line number Diff line
@@ -2113,13 +2113,17 @@ int get_msr(int cpu, off_t offset, unsigned long long *msr) 
int probe_msr(int cpu, off_t offset)

{

	ssize_t retval;

	unsigned long long dummy;

	unsigned long long value;



	assert(!no_msr);



	retval = pread(get_msr_fd(cpu), &dummy, sizeof(dummy), offset);

	retval = pread(get_msr_fd(cpu), &value, sizeof(value), offset);



	if (retval != sizeof(dummy))

	/*

	 * Expect MSRs to accumulate some non-zero value since the system was powered on.

	 * Treat zero as a read failure.

	 */

	if (retval != sizeof(value) || value == 0)

		return 1;



	return 0;