tools/power turbostat: work around RC6 counter wrap

Sometimes the rc6 sysfs counter spontaneously resets,
causing turbostat prints a very large number
as it tries to calcuate % = 100 * (old - new) / interval

When we see (old > new), print ***.**% instead
of a bogus huge number.

Note that this detection is not fool-proof, as the counter
could reset several times and still result in new > old.

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 277e032..d2ae87d 100644 (file)
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -189,7 +189,7 @@ struct pkg_data {
        unsigned long long pkg_any_core_c0;
        unsigned long long pkg_any_gfxe_c0;
        unsigned long long pkg_both_core_gfxe_c0;
-       unsigned long long gfx_rc6_ms;
+       long long gfx_rc6_ms;
        unsigned int gfx_mhz;
        unsigned int package_id;
        unsigned int energy_pkg;        /* MSR_PKG_ENERGY_STATUS */
@@ -623,8 +623,14 @@ int format_counters(struct thread_data *t, struct core_data *c,
                outp += sprintf(outp, "%8d", p->pkg_temp_c);
 
        /* GFXrc6 */
-       if (do_gfx_rc6_ms)
-               outp += sprintf(outp, "%8.2f", 100.0 * p->gfx_rc6_ms / 1000.0 / interval_float);
+       if (do_gfx_rc6_ms) {
+               if (p->gfx_rc6_ms == -1) {      /* detect counter reset */
+                       outp += sprintf(outp, "  ***.**");
+               } else {
+                       outp += sprintf(outp, "%8.2f",
+                               p->gfx_rc6_ms / 10.0 / interval_float);
+               }
+       }
 
        /* GFXMHz */
        if (do_gfx_mhz)
@@ -768,7 +774,12 @@ delta_package(struct pkg_data *new, struct pkg_data *old)
        old->pc10 = new->pc10 - old->pc10;
        old->pkg_temp_c = new->pkg_temp_c;
 
-       old->gfx_rc6_ms = new->gfx_rc6_ms - old->gfx_rc6_ms;
+       /* flag an error when rc6 counter resets/wraps */
+       if (old->gfx_rc6_ms >  new->gfx_rc6_ms)
+               old->gfx_rc6_ms = -1;
+       else
+               old->gfx_rc6_ms = new->gfx_rc6_ms - old->gfx_rc6_ms;
+
        old->gfx_mhz = new->gfx_mhz;
 
        DELTA_WRAP32(new->energy_pkg, old->energy_pkg);