Re: cpufreq est and Enhanced Sleep (Cx) States for Intel Core and above
- From: "Stephane E. Potvin" <sepotvin@xxxxxxxxxxxx>
- Date: Mon, 12 Feb 2007 22:53:24 -0500
Adam McDougall wrote:
On Wed, Dec 13, 2006 at 12:14:55PM -0500, Stephane E. Potvin wrote:
Adam McDougall wrote:
>On Sat, Dec 09, 2006 at 07:29:23PM -0500, Adam McDougall wrote:
>
> Another thing I wish could work is the Enhanced cpu Sleep States;
> this Dell Latitude D820 laptop only sees C1 although the document
> above indicates it should probably support 4 unique states. Is
> there a way I can debug and/or fix this? I can post dumps of the
> acpi stuff and/or verbose boot logs if it would be helpful.
>
> Thanks
> _______________________________________________
>
>I am attaching my asl and dsdt acpi dumps incase someone knows for
>something to look for as for why it thinks I only have C1, unless
>its related to the speed control problem above.
>
Hi Adam,
It's only finding the C1 state for various reasons that you'll find
described in some details in the following email that I send to the acpi
mailing list in June this year. The major reason being that the acpi cpu
driver does not support well multiprocessor systems.
http://docs.freebsd.org/cgi/getmsg.cgi?fetch=116103+0+archive/2006/freebsd-acpi/20060611.freebsd-acpi
The email also included a patch to add support for multiprocessor
systems to the acpi cpu driver. I've not updated the patch since then so
it might or might not apply cleanly to a recent current.
Steph
I didn't get around to trying that patch, but I have tried -current
after code was committed, including as late as Feb 11. It seems to work,
but if both of my cpus are allowed to enter C3 state, my laptop
clock stops advancing (unless you are causing activity) and the performance
gets very choppy, including mouse cursor halting for a second or two, etc.
Typing or moving the mouse seems to nudge the system into crawling along,
but if I leave it alone, timing loops stall. I could do a while loop with
a sleep on the command line and time just doesn't advance on its own, and
the clock in Gnome would halt. My laptop is using the Hpet timer, but it
doesn't seem to make a difference if I use sysctl to try ACPI-fast or i8254.
Could you try the attached patch on your system? It adds a crude check
to make sure that the system is not sleeping for more than 1/hz secs.
The acpi_cpu driver should back off to a lower Cx state if it does.
Steph
Index: acpi_cpu.c
===================================================================
RCS file: /home/FreeBSD/ncvs/src/sys/dev/acpica/acpi_cpu.c,v
retrieving revision 1.63
diff -u -r1.63 acpi_cpu.c
--- acpi_cpu.c 23 Jan 2007 07:20:44 -0000 1.63
+++ acpi_cpu.c 13 Feb 2007 03:28:32 -0000
@@ -80,6 +80,7 @@
/* Runtime state. */
int cpu_non_c3; /* Index of lowest non-C3 state. */
int cpu_short_slp; /* Count of < 1us sleeps. */
+ int cpu_long_slp; /* Count of > hz sleeps. */
u_int cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */
/* Values for sysctl. */
struct sysctl_ctx_list cpu_sysctl_ctx;
@@ -123,6 +124,9 @@
static int cpu_disable_idle; /* Disable entry to idle function */
static int cpu_cx_count; /* Number of valid Cx states */
+/* Longest allowable sleep */
+static int cpu_max_sleep = 0;
+
/* Values for sysctl. */
static struct sysctl_ctx_list cpu_sysctl_ctx;
static struct sysctl_oid *cpu_sysctl_tree;
@@ -278,6 +282,9 @@
cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
+ sc->cpu_short_slp = 0;
+ sc->cpu_long_slp = 0;
+
buf.Pointer = NULL;
buf.Length = ACPI_ALLOCATE_BUFFER;
status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
@@ -311,6 +318,10 @@
/* Queue post cpu-probing task handler */
AcpiOsQueueForExecution(OSD_PRIORITY_LO, acpi_cpu_startup, NULL);
+
+ /* Setup the longest allowable sleep */
+ cpu_max_sleep = 1000000 / hz;
+ cpu_max_sleep *= 10;
}
/*
@@ -832,10 +843,17 @@
* that both cores will get out of C3 state as soon as one of them
* requires it. This breaks the sleep detection logic as the sleep
* counter is local to each cpu. Disable the sleep logic for now as a
- * workaround if there's more than one CPU. The right fix would probably
- * be to add quirks for system that don't really support C3 state.
+ * workaround if we have more than one cpus and some of them are.
+ * logical (more than one core per package). The right fix would
+ * probably be to add quirks for system that don't really support
+ * C3 state.
*/
- if (mp_ncpus < 2 && sc->cpu_prev_sleep <= 1) {
+#ifdef SMP
+ if (((mp_ncpus >= 2 && logical_cpus_mask == 0) || mp_ncpus < 2)
+ && sc->cpu_prev_sleep <= 1) {
+#else
+ if (sc->cpu_prev_sleep <= 1) {
+#endif
sc->cpu_short_slp++;
if (sc->cpu_short_slp == 1000 && sc->cpu_cx_lowest != 0) {
if (sc->cpu_non_c3 == sc->cpu_cx_lowest && sc->cpu_non_c3 != 0)
@@ -849,6 +867,26 @@
} else
sc->cpu_short_slp = 0;
+ /*
+ * If we keep sleeping for more than 1 hz it may indicate a broken
+ * system where the clock will not fire anymore in low Cx states.
+ * Keep backing off in this case until we start getting back clock
+ * interrupts.
+ */
+ if (sc->cpu_prev_sleep > cpu_max_sleep) {
+ sc->cpu_long_slp++;
+ if (sc->cpu_long_slp == 10 && sc->cpu_cx_lowest != 0) {
+ if (sc->cpu_non_c3 == sc->cpu_cx_lowest && sc->cpu_non_c3 != 0)
+ sc->cpu_non_c3--;
+ sc->cpu_cx_lowest--;
+ sc->cpu_long_slp = 0;
+ device_printf(sc->cpu_dev,
+ "too many long sleeps, backing off to C%d\n",
+ sc->cpu_cx_lowest + 1);
+ }
+ } else
+ sc->cpu_long_slp = 0;
+
for (i = sc->cpu_cx_lowest; i >= 0; i--)
if (sc->cpu_cx_states[i].trans_lat <= sc->cpu_prev_sleep) {
cx_next_idx = i;
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