Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c3ae331d authored by Len Brown's avatar Len Brown
Browse files

tools/power: turbostat: fix large c1% issue 



Under some conditions, c1% was displayed as very large number,
much higher than 100%.

c1% is not measured, it is derived as "that, which is left over"
from other counters.  However, the other counters are not collected
atomically, and so it is possible for c1% to be calaculagted as
a small negative number -- displayed as very large positive.

There was a check for mperf vs tsc for this already,
but it needed to also include the other counters
that are used to calculate c1.

Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent c98d5d94

tools/power/x86/turbostat/turbostat.c

+8 −4
Original line number Diff line number Diff line
@@ -444,6 +444,9 @@ delta_core(struct core_data *new, struct core_data *old) 
	old->c7 = new->c7 - old->c7;

}



/*

 * old = new - old

 */

void

delta_thread(struct thread_data *new, struct thread_data *old,

	struct core_data *core_delta)
@@ -482,19 +485,20 @@ delta_thread(struct thread_data *new, struct thread_data *old, 




	/*

	 * As mperf and tsc collection are not atomic,

	 * it is possible for mperf's non-halted cycles

	 * As counter collection is not atomic,

	 * it is possible for mperf's non-halted cycles + idle states

	 * to exceed TSC's all cycles: show c1 = 0% in that case.

	 */

	if (old->mperf > old->tsc)

	if ((old->mperf + core_delta->c3 + core_delta->c6 + core_delta->c7) > old->tsc)

		old->c1 = 0;

	else {

		/* normal case, derive c1 */

		old->c1 = old->tsc - old->mperf - core_delta->c3

				- core_delta->c6 - core_delta->c7;

	}



	if (old->mperf == 0) {

		if (verbose) fprintf(stderr, "cpu%d MPERF 0!\n", old->cpu_id);

		if (verbose > 1) fprintf(stderr, "cpu%d MPERF 0!\n", old->cpu_id);

		old->mperf = 1;	/* divide by 0 protection */

	}