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From: Pierre Ossman <drzeus-list@drzeus.cx>
To: unlisted-recipients:; (no To-header on input)
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	"Dave Jones" <davej@codemonkey.org.uk>,
	"Andi Kleen" <andi@firstfloor.org>,
	"Alan Stern" <stern@rowland.harvard.edu>,
	"LKML" <linux-kernel@vger.kernel.org>,
	"Adam Belay" <abelay@novell.com>,
	"Lee Revell" <rlrevell@joe-job.com>,
	linux-pm@lists.linux-foundation.org,
	"Pavel  Machek" <pavel@ucw.cz>
Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors
Date: Thu, 6 Mar 2008 09:27:30 +0100	[thread overview]
Message-ID: <20080306092730.4412d085@mjolnir.drzeus.cx> (raw)
In-Reply-To: <20080305094023.6486ebdf@mjolnir.drzeus.cx>

On Wed, 5 Mar 2008 09:40:23 +0100
Pierre Ossman <drzeus-list@drzeus.cx> wrote:

> 
> So I need to build some global algorithm instead of one per core. Ideas are welcome.
> 

I'm currently trying this variant. No noise yet, but the time spent in C3 seems to take a massive hit. I'll see if I can get around to some kind of power measurement (ideas for doing that in a sane way are still welcome btw).

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 78d77c5..960aa39 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -16,6 +16,11 @@
 
 #define BREAK_FUZZ	4	/* 4 us */
 
+static unsigned int min_deep_sleep = 0;
+static unsigned int failed_deep = 0;
+
+static unsigned long global_last_deep;
+
 struct menu_device {
 	int		last_state_idx;
 
@@ -23,6 +28,8 @@ struct menu_device {
 	unsigned int	predicted_us;
 	unsigned int	last_measured_us;
 	unsigned int	elapsed_us;
+
+	unsigned long	last_deep;
 };
 
 static DEFINE_PER_CPU(struct menu_device, menu_devices);
@@ -50,9 +57,51 @@ static int menu_select(struct cpuidle_device *dev)
 			break;
 		if (s->exit_latency > pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY))
 			break;
+
+		/*
+		 * In order to avoid the problem of "singing capacitors",
+		 * don't enter a deep sleep for short durations (2 ms seems
+		 * to do the trick). This will, hopefully, keep the problem
+		 * inaudible.
+		 */
+		if (min_deep_sleep && (s->flags & CPUIDLE_FLAG_DEEP)) {
+			if (time_before_eq(jiffies, data->last_deep +
+				HZ * min_deep_sleep / USEC_PER_SEC))
+				break;
+
+			rmb();
+
+			if (time_before_eq(jiffies, global_last_deep +
+				HZ * min_deep_sleep / USEC_PER_SEC))
+				break;
+
+#if 0
+			if (min_deep_sleep > data->expected_us)
+				break;
+			if (min_deep_sleep > cpuidle_get_last_residency(dev))
+				break;
+#endif
+#if 0
+			if (min_deep_sleep > data->predicted_us)
+				break;
+			if (min_deep_sleep > data->last_measured_us)
+				break;
+#endif
+		}
 	}
 
 	data->last_state_idx = i - 1;
+
+	if (dev->states[i - 1].flags & CPUIDLE_FLAG_DEEP) {
+#if 0
+		printk("Sleep interval: %ld jiffies\n",
+			jiffies - data->last_deep);
+#endif
+		data->last_deep = jiffies;
+		global_last_deep = jiffies;
+		wmb();
+	}
+
 	return i - 1;
 }
 
@@ -80,6 +129,15 @@ static void menu_reflect(struct cpuidle_device *dev)
 	if (!(target->flags & CPUIDLE_FLAG_TIME_VALID))
 		measured_us = USEC_PER_SEC / HZ;
 
+	if ((target->flags & CPUIDLE_FLAG_DEEP) &&
+	    (cpuidle_get_last_residency(dev) < min_deep_sleep)) {
+#if 0
+		printk("F: %d / %d,%d\n", cpuidle_get_last_residency(dev),
+			data->expected_us,data->predicted_us);
+#endif
+		failed_deep++;
+	}
+
 	/* Predict time remaining until next break event */
 	if (measured_us + BREAK_FUZZ < data->expected_us - target->exit_latency) {
 		data->predicted_us = max(measured_us, data->last_measured_us);
@@ -102,7 +160,14 @@ static int menu_enable_device(struct cpuidle_device *dev)
 {
 	struct menu_device *data = &per_cpu(menu_devices, dev->cpu);
 
+	printk("Attaching menu governor...\n");
+
 	memset(data, 0, sizeof(struct menu_device));
+	/*
+	 * 0 might be slightly ahead of the current jiffies count, so
+	 * it's a bad initial value.
+	 */
+	data->last_deep = jiffies;
 
 	return 0;
 }
@@ -121,6 +186,8 @@ static struct cpuidle_governor menu_governor = {
  */
 static int __init init_menu(void)
 {
+	global_last_deep = jiffies;
+
 	return cpuidle_register_governor(&menu_governor);
 }
 
@@ -132,6 +199,11 @@ static void __exit exit_menu(void)
 	cpuidle_unregister_governor(&menu_governor);
 }
 
+module_param(min_deep_sleep, uint, 0644)
+MODULE_PARM_DESC(min_deep_sleep, "min time (us) to spend in deep sleep to avoid noise")
+
+module_param(failed_deep, uint, 0644)
+
 MODULE_LICENSE("GPL");
 module_init(init_menu);
 module_exit(exit_menu);


Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

  parent reply	other threads:[~2008-03-06  8:29 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29 18:38 [RFC][PATCH] " Pierre Ossman
2008-02-29 21:44 ` Lennart Sorensen
2008-03-01 12:31   ` Pierre Ossman
2008-03-01 13:40 ` Pierre Ossman
2008-03-02  2:27 ` Lee Revell
2008-03-02 14:17   ` Pierre Ossman
2008-03-03 12:36 ` Andi Kleen
2008-03-03 20:18 ` [PATCH] " Pierre Ossman
2008-03-03 20:46   ` Pavel Machek
2008-03-03 21:03     ` Pierre Ossman
2008-03-03 21:08       ` Pavel Machek
2008-03-03 21:14         ` Pallipadi, Venkatesh
2008-03-03 21:17           ` Pierre Ossman
2008-03-03 22:04             ` Pallipadi, Venkatesh
2008-03-03 23:05               ` [linux-pm] " Alan Stern
2008-03-03 23:10                 ` Andi Kleen
2008-03-04  4:00                   ` Dave Jones
2008-03-04  6:14                     ` Pierre Ossman
2008-03-04 17:19                       ` Pierre Ossman
2008-03-04 17:29                         ` Andi Kleen
2008-03-04 17:30                           ` Pierre Ossman
2008-03-04 17:43                             ` Andi Kleen
2008-03-04 18:04                               ` Pierre Ossman
2008-03-04 18:34                                 ` Andi Kleen
2008-03-05  6:04                                   ` Pierre Ossman
2008-03-05 15:48                                     ` Andi Kleen
2008-03-05 16:53                                       ` Pierre Ossman
2008-03-05 17:32                                         ` Andi Kleen
2008-03-04 19:01                         ` Pallipadi, Venkatesh
2008-03-05  6:02                           ` Pierre Ossman
2008-03-05  8:40                             ` Pierre Ossman
2008-03-05  9:03                               ` Pavel Machek
2008-03-05 13:42                                 ` Pierre Ossman
2008-03-05 13:47                                   ` Pavel Machek
2008-03-05 13:52                                     ` Pierre Ossman
2008-03-06  8:27                               ` Pierre Ossman [this message]
2008-03-09 14:16                                 ` Pierre Ossman
2008-03-09 18:19                                   ` Rafael J. Wysocki
2008-03-09 18:50                                   ` Alan Stern
2008-03-09 19:30                                   ` Henrique de Moraes Holschuh
2008-03-09 20:14                                     ` Pierre Ossman
2008-03-09 20:41                                       ` Henrique de Moraes Holschuh
2008-03-09 20:54                                         ` Henrique de Moraes Holschuh
2008-03-10 10:00                                   ` Pavel Machek
2008-03-10 12:49                                     ` Pierre Ossman
2008-03-10 13:04                                       ` Andi Kleen
2008-03-10 13:29                                         ` Pierre Ossman
2008-03-12 19:11                                       ` Len Brown
2008-03-13  8:10                                         ` Pavel Machek
2008-03-13 10:42                                           ` Andi Kleen
2008-03-14  4:13                                             ` Len Brown
2008-03-13 16:34                                         ` Pierre Ossman
2008-03-13 16:47                                           ` Pallipadi, Venkatesh
2008-03-13 17:44                                             ` Pierre Ossman
2008-03-13 17:49                                           ` Pierre Ossman
2008-03-14 19:40                                           ` Pierre Ossman
2008-03-14 21:15                                             ` Pallipadi, Venkatesh
2008-03-15  0:41                                               ` Pierre Ossman
2008-03-11  7:51                                   ` Pierre Ossman
2008-03-11 10:48                                     ` Andi Kleen
2008-03-11 15:20                                       ` Pierre Ossman
2008-03-11 17:31                                         ` Pierre Ossman
2008-03-12 19:17                                       ` Len Brown
2008-03-12 20:31                               ` Len Brown
2008-03-04  9:40                     ` Andi Kleen
2008-03-03 23:09               ` Andi Kleen

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