Bill.Holler wrote:
> Can't this code can just read the TSC directly with something like
> tsc_read(). :-) Both gethrtime() calls are done with interrupts
> disabled on the same CPU just before and after going into
> Deep C-State. Interrups are not enabled between the two
> gethrtime() calls. The two TSC values will be accurate with each
> other during this interval. A difference is computed,
> so tsc_sync_tick_delta is not needed.
>
> The TSC difference will have to be scaled to nonoseconds
> with something like tsc_scalehrtime.
>
Do you mean the following change? :-)
I tried it yesterday, I still saw 80%~ in C0 in powertop when system is
idle.
Current cstate of most cpus are also in C0. But vmstat and mpstat shows
that idle is almost 100%(obtained from mstate). I didn't figure out
yesterday.
Did I miss anything?
Thanks,
-Aubrey
=================================================================
diff -r 6adc6a654072 usr/src/uts/i86pc/io/cpudrv/cpu_idle.c
--- a/usr/src/uts/i86pc/io/cpudrv/cpu_idle.c Thu Sep 04 13:40:03 2008
+0800
+++ b/usr/src/uts/i86pc/io/cpudrv/cpu_idle.c Fri Sep 05 14:00:00 2008
+0800
@@ -414,7 +414,7 @@
/* DTRACE_PROBE1(idle__state__transition, uint_t,
(uint_t)cs_type); */
cpu_dtrace_idle_probe((uint_t)cs_type);
- start = gethrtime();
+ start = tsc_read();
(void) snprintf(mcpu->curr_cstate, KSTAT_STRLEN - 1,
"C%d", cs_type);
if (type == ACPI_ADR_SPACE_FIXED_HARDWARE) {
@@ -507,9 +507,15 @@
}
(void) snprintf(mcpu->curr_cstate, KSTAT_STRLEN - 1,
"C%d", CPU_ACPI_C0);
- delta = (gethrtime() - start) / 1000ul;
+ delta = tsc_read() - start;
/* DTRACE_PROBE1(idle__state__transition, uint_t, CPU_ACPI_C0);
*/
cpu_dtrace_idle_probe(CPU_ACPI_C0);
+
+ /*
+ * Convert delta in macroseconds
+ */
+ scalehrtimef(&delta);
+ delta = delta / 1000ul;
/*
* We're no longer halted
@@ -591,13 +597,18 @@
switch (cs_type) {
case CPU_ACPI_C1:
- start = gethrtime();
+ start = tsc_read();
(void) snprintf(mcpu->curr_cstate, KSTAT_STRLEN - 1,
"C%d", cs_type);
(*CPU->shadow_idle_cpu)();
(void) snprintf(mcpu->curr_cstate, KSTAT_STRLEN - 1,
"C%d", CPU_ACPI_C0);
- delta = (gethrtime() - start) / 1000ul;
+ delta = tsc_read() - start;
+ /*
+ * Convert delta in macroseconds
+ */
+ scalehrtimef(&delta);
+ delta = delta / 1000ul;
break;
case CPU_ACPI_C2:
