svn commit: r209897 - stable/8/sys/dev/acpica

[Alexander Motin]

Author: mav
Date: Sun Jul 11 11:58:46 2010
New Revision: 209897
URL: http://svn.freebsd.org/changeset/base/209897

Log:
  MFC r209328,r209330:
  While we indeed can't precisely measure time spent in C1, we can consider
  measured interval as upper bound. It should be more precise then just
  assuming 1/(2*hz). For idle CPU it should be quite precise, for busy - not
  worse then before.

Modified:
  stable/8/sys/dev/acpica/acpi_cpu.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/xen/xenpci/   (props changed)

Modified: stable/8/sys/dev/acpica/acpi_cpu.c
==============================================================================
--- stable/8/sys/dev/acpica/acpi_cpu.c	Sun Jul 11 09:37:34 2010	(r209896)
+++ stable/8/sys/dev/acpica/acpi_cpu.c	Sun Jul 11 11:58:46 2010	(r209897)
@@ -930,12 +930,16 @@ acpi_cpu_idle()
 
     /*
      * Execute HLT (or equivalent) and wait for an interrupt.  We can't
-     * calculate the time spent in C1 since the place we wake up is an
-     * ISR.  Assume we slept half of quantum and return.
+     * precisely calculate the time spent in C1 since the place we wake up
+     * is an ISR.  Assume we slept no more then half of quantum.
      */
     if (cx_next->type == ACPI_STATE_C1) {
-	sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 + 500000 / hz) / 4;
+	AcpiHwRead(&start_time, &AcpiGbl_FADT.XPmTimerBlock);
 	acpi_cpu_c1();
+	AcpiHwRead(&end_time, &AcpiGbl_FADT.XPmTimerBlock);
+        end_time = acpi_TimerDelta(end_time, start_time);
+	sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 +
+	    min(PM_USEC(end_time), 500000 / hz)) / 4;
 	return;
     }