Re: Performance/resume issues on Toshiba NB305

Seth Forshee
2011-03-01T20:04:56Z

On Fri, Feb 25, 2011 at 10:47:16PM +0100, Thomas Gleixner wrote:
> On Fri, 25 Feb 2011, Seth Forshee wrote:
> > On Fri, Feb 25, 2011 at 09:37:39PM +0100, Thomas Gleixner wrote:
> > > On Fri, 25 Feb 2011, Seth Forshee wrote:
> > > That seems to be related to low power states. When the machine goes
> > > idle we switch into lower power states and that requires to use the
> > > hpet instead of the local apic timer as that one stops.
> > >
> > > You could verify that theory by booting with processor.max_cstate=1
> >
> > This fixes the performance in combination with intel_idle.max_cstate=0.
> > Alternately, intel_idle.max_cstate=1 works. But the resume still hangs.
>
> That was expected :)
>
> > Is the answer to quirk the machine to avoid deep C-states, or is there
> > some better way I can fix this?
>
> Let's wait for the intel and acpi folks. It would be interesting what
> the new intel toy says to your BIOS.

Since the discussion on this issue died without really getting anywhere,
I went ahead and threw together the patch below to disable anything
deeper than C1 for this machine. I hope a better solution can be found,
but if not would something like this be an acceptable workaround?

As for the hangs during resume, unless someone has a better suggestion I
guess I'll start looking into forcing the HPET to remain in periodic
mode throughout suspend.

Thanks,
Seth

---

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 1fa091e..7d88540 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -61,6 +61,7 @@
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
+#include <linux/dmi.h>
#include <asm/mwait.h>

#define INTEL_IDLE_VERSION "0.4"
@@ -441,6 +442,32 @@ static int intel_idle_cpuidle_devices_init(void)
}

+/*
+ * dmi_disable_cstates()
+ * Disable states beyond C1 for broken machines
+ */
+static int __init dmi_disable_cstates(const struct dmi_system_id *d)
+{
+ if (max_cstate == MWAIT_MAX_NUM_CSTATES - 1) {
+ pr_notice(PREFIX "%s detected, disabling C-states past C1\n",
+ d->ident);
+ max_cstate = 1;
+ }
+}
+
+/* List of systems with known idle problems */
+static struct dmi_system_id __initdata bad_cstate_dmi_table[] = {
+ {
+ .callback = dmi_disable_cstates,
+ .ident = "Toshiba NB305",
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR, "TOSHIBA"),
+ DMI_MATCH(DMI_BOARD_NAME, "NPVAA"),
+ },
+ },
+ {}
+};
+
static int __init intel_idle_init(void)
{
int retval;
@@ -449,6 +476,9 @@ static int __init intel_idle_init(void)
if (boot_option_idle_override != IDLE_NO_OVERRIDE)
return -ENODEV;

+ /* Check for known-bad hardware */
+ dmi_check_system(bad_cstate_dmi_table);
+
retval = intel_idle_probe();
if (retval)
return retval;
--
1.7.4.1