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Date: Thu, 8 Nov 2007 14:30:07 -0800
From: Mark Gross <mgross@...ux.intel.com>
To: Valdis.Kletnieks@...edu
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Subject: Re: 2.6.23-mm1 breaks C-state support on Intel T7200 x86_64
On Thu, Nov 08, 2007 at 12:19:44PM -0500, Valdis.Kletnieks@...edu wrote:
> (Sorry for not reporting this sooner - I haven't been running off battery
> much in the last 3 weeks, so I didn't notice it till now...)
>
> Dell Latitude D820 laptop, T7200 Core2 Duo CPU, x86_64 kernel.
>
> As reported by 'powertop' on a basically idle machine:
>
> 2.6.23-mm1:
>
> Cn Avg residency P-states (frequencies)
> C0 (cpu running) (100.0%) 2.00 Ghz 0.8%
> C1 0.0ms ( 0.0%) 1.67 Ghz 0.0%
> C2 0.0ms ( 0.0%) 1333 Mhz 0.0%
> C3 0.0ms ( 0.0%) 1000 Mhz 99.2%
>
> 2.6.23-rc8-mm2:
>
> Cn Avg residency P-states (frequencies)
> C0 (cpu running) ( 0.3%) 2.00 Ghz 0.0%
> C1 0.0ms ( 0.0%) 1.67 Ghz 0.0%
> C2 0.0ms ( 0.0%) 1333 Mhz 0.0%
> C3 31.5ms (99.7%) 1000 Mhz 100.0%
>
> In addition, the ACPI power estimate reported about 25 watts for 23-mm1,
> but only 21 watts for -rc8-mm2, a significant regression.
>
> I bisected this down to this set of patches:
>
> pm-qos-infrastructure-and-interface.patch
> pm-qos-infrastructure-and-interface-fix.patch
> pm-qos-infrastructure-and-interface-vs-git-acpi.patch
> pm-qos-infrastructure-and-interface-vs-git-acpi-2.patch
> latencyc-use-qos-infrastructure.patch
>
> The patch says:
>
> To register the default pm_qos target for the specific parameter, the
> process must open one of /dev/[cpu_dma_latency, network_latency,
> network_throughput]
>
> As long as the device node is held open that process has a registered
> requirement on the parameter. The name of the requirement is
> "process_<PID>" derived from the current->pid from within the open system
> call.
>
> I shouldn't have to have a process open a /dev/file, write a number, and then
> stay around forever so the file doesn't close in order to get the same behavior
> I was getting by default before. What needs to happen to get this to not
> be a behavior regression/change?
>
>
>
>
wing patch fixes up the cpuidle / pm-qos integration.
I suspect that this is folded into another mm patch but it should fix
C-state issue identified.
--mgross
Signed-off-by: mark gross <mgross@...ux.intel.com>
-------------
Index: linux-2.6.23-mm1/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-2.6.23-mm1.orig/drivers/cpuidle/cpuidle.c 2007-11-08 13:09:53.000000000 -0800
+++ linux-2.6.23-mm1/drivers/cpuidle/cpuidle.c 2007-11-08 13:25:13.000000000 -0800
@@ -268,7 +268,7 @@
static inline void latency_notifier_init(struct notifier_block *n)
{
- pm_qos_add_notifier(PM_QOS_CPUIDLE, n);
+ pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
}
#else /* CONFIG_SMP */
Index: linux-2.6.23-mm1/drivers/cpuidle/governors/ladder.c
===================================================================
--- linux-2.6.23-mm1.orig/drivers/cpuidle/governors/ladder.c 2007-11-08 13:09:53.000000000 -0800
+++ linux-2.6.23-mm1/drivers/cpuidle/governors/ladder.c 2007-11-08 13:11:30.000000000 -0800
@@ -82,7 +82,7 @@
if (last_idx < dev->state_count - 1 &&
last_residency > last_state->threshold.promotion_time &&
dev->states[last_idx + 1].exit_latency <=
- pm_qos_requirement(PM_QOS_CPUIDLE)) {
+ pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY)) {
last_state->stats.promotion_count++;
last_state->stats.demotion_count = 0;
if (last_state->stats.promotion_count >= last_state->threshold.promotion_count) {
Index: linux-2.6.23-mm1/drivers/cpuidle/governors/menu.c
===================================================================
--- linux-2.6.23-mm1.orig/drivers/cpuidle/governors/menu.c 2007-11-08 13:12:11.000000000 -0800
+++ linux-2.6.23-mm1/drivers/cpuidle/governors/menu.c 2007-11-08 13:24:03.000000000 -0800
@@ -48,7 +48,8 @@
break;
if (s->target_residency > data->predicted_us)
break;
- if (s->exit_latency > pm_qos_requirement(PM_QOS_CPUIDLE))
+ if (s->exit_latency >
+ pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY))
break;
}
Index: linux-2.6.23-mm1/include/linux/pm_qos_params.h
===================================================================
--- linux-2.6.23-mm1.orig/include/linux/pm_qos_params.h 2007-11-08 13:09:53.000000000 -0800
+++ linux-2.6.23-mm1/include/linux/pm_qos_params.h 2007-11-08 13:14:05.000000000 -0800
@@ -6,23 +6,12 @@
#include <linux/notifier.h>
#include <linux/miscdevice.h>
-struct requirement_list {
- struct list_head list;
- union {
- s32 value;
- s32 usec;
- s32 kbps;
- };
- char *name;
-};
-
#define PM_QOS_RESERVED 0
#define PM_QOS_CPU_DMA_LATENCY 1
#define PM_QOS_NETWORK_LATENCY 2
#define PM_QOS_NETWORK_THROUGHPUT 3
-#define PM_QOS_CPUIDLE 4
-#define PM_QOS_NUM_CLASSES 5
+#define PM_QOS_NUM_CLASSES 4
#define PM_QOS_DEFAULT_VALUE -1
int pm_qos_add_requirement(int qos, char *name, s32 value);
Index: linux-2.6.23-mm1/kernel/pm_qos_params.c
===================================================================
--- linux-2.6.23-mm1.orig/kernel/pm_qos_params.c 2007-11-08 13:09:54.000000000 -0800
+++ linux-2.6.23-mm1/kernel/pm_qos_params.c 2007-11-08 13:14:28.000000000 -0800
@@ -47,6 +47,16 @@
* held, taken with _irqsave. One lock to rule them all
*/
+struct requirement_list {
+ struct list_head list;
+ union {
+ s32 value;
+ s32 usec;
+ s32 kbps;
+ };
+ char *name;
+};
+
struct pm_qos_object {
struct requirement_list requirements;
struct srcu_notifier_head notifiers;
-
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