Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762143AbYCFI3U (ORCPT ); Thu, 6 Mar 2008 03:29:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756854AbYCFI3M (ORCPT ); Thu, 6 Mar 2008 03:29:12 -0500 Received: from gateway.drzeus.cx ([85.8.24.16]:51052 "EHLO smtp.drzeus.cx" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755668AbYCFI3L (ORCPT ); Thu, 6 Mar 2008 03:29:11 -0500 Date: Thu, 6 Mar 2008 09:27:30 +0100 From: Pierre Ossman Cc: "Pallipadi, Venkatesh" , "Dave Jones" , "Andi Kleen" , "Alan Stern" , "LKML" , "Adam Belay" , "Lee Revell" , linux-pm@lists.linux-foundation.org, "Pavel Machek" Subject: Re: [linux-pm] [PATCH] cpuidle: avoid singing capacitors Message-ID: <20080306092730.4412d085@mjolnir.drzeus.cx> In-Reply-To: <20080305094023.6486ebdf@mjolnir.drzeus.cx> References: <924EFEDD5F540B4284297C4DC59F3DEEA2E8B2@orsmsx423.amr.corp.intel.com> <20080303231033.GB15255@one.firstfloor.org> <20080304040048.GA31562@codemonkey.org.uk> <20080304071423.0e6b71c1@mjolnir.drzeus.cx> <20080304181924.70aaf8c1@mjolnir.drzeus.cx> <924EFEDD5F540B4284297C4DC59F3DEEA77031@orsmsx423.amr.corp.intel.com> <20080305070201.0d16cd40@mjolnir.drzeus.cx> <20080305094023.6486ebdf@mjolnir.drzeus.cx> X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.8; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4276 Lines: 152 On Wed, 5 Mar 2008 09:40:23 +0100 Pierre Ossman 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/