Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757542Ab1BKAtu (ORCPT ); Thu, 10 Feb 2011 19:49:50 -0500 Received: from mga02.intel.com ([134.134.136.20]:50971 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756906Ab1BKAts (ORCPT ); Thu, 10 Feb 2011 19:49:48 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.60,452,1291622400"; d="scan'208";a="601533470" Subject: Re: [Patch] idle governor: Avoid lock acquisition to read pm_qos before entering idle From: Tim Chen To: "Rafael J. Wysocki" Cc: mark gross , James Bottomley , David Alan Gilbert , linux-kernel@vger.kernel.org, Len , Andi Kleen , Arjan van de Ven , Len Brown , Linux PM mailing list In-Reply-To: <201102110017.16066.rjw@sisk.pl> References: <1297300864.2645.128.camel@schen9-DESK> <201102110017.16066.rjw@sisk.pl> Content-Type: text/plain; charset="UTF-8" Date: Thu, 10 Feb 2011 16:50:16 -0800 Message-ID: <1297385416.2645.262.camel@schen9-DESK> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 (2.28.3-1.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4221 Lines: 132 On Fri, 2011-02-11 at 00:17 +0100, Rafael J. Wysocki wrote: > > +static inline int pm_qos_set_value(struct pm_qos_object *o, s32 value) > > +{ > > + o->value = value; > > +} > > This requires a fixup, the above function is supposed to return an int. > > Also, please add a comment about the requisite 32-bitness as suggested by James. > > Thanks, > Rafael I've fixed the above function, and also included a comment warning people not to change target value to 64 bit. Thanks. Tim Signed-off-by: Tim Chen diff --git a/include/linux/pm_qos_params.h b/include/linux/pm_qos_params.h index 77cbddb..a7d87f9 100644 --- a/include/linux/pm_qos_params.h +++ b/include/linux/pm_qos_params.h @@ -16,6 +16,10 @@ #define PM_QOS_NUM_CLASSES 4 #define PM_QOS_DEFAULT_VALUE -1 +#define PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC) +#define PM_QOS_NETWORK_LAT_DEFAULT_VALUE (2000 * USEC_PER_SEC) +#define PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE 0 + struct pm_qos_request_list { struct plist_node list; int pm_qos_class; diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c index aeaa7f8..7b6333b 100644 --- a/kernel/pm_qos_params.c +++ b/kernel/pm_qos_params.c @@ -58,6 +58,7 @@ struct pm_qos_object { struct blocking_notifier_head *notifiers; struct miscdevice pm_qos_power_miscdev; char *name; + s32 target_value; /* Do not change this to 64 bit */ s32 default_value; enum pm_qos_type type; }; @@ -70,7 +71,8 @@ static struct pm_qos_object cpu_dma_pm_qos = { .requests = PLIST_HEAD_INIT(cpu_dma_pm_qos.requests, pm_qos_lock), .notifiers = &cpu_dma_lat_notifier, .name = "cpu_dma_latency", - .default_value = 2000 * USEC_PER_SEC, + .target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, + .default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE, .type = PM_QOS_MIN, }; @@ -79,7 +81,8 @@ static struct pm_qos_object network_lat_pm_qos = { .requests = PLIST_HEAD_INIT(network_lat_pm_qos.requests, pm_qos_lock), .notifiers = &network_lat_notifier, .name = "network_latency", - .default_value = 2000 * USEC_PER_SEC, + .target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE, + .default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE, .type = PM_QOS_MIN }; @@ -89,7 +92,8 @@ static struct pm_qos_object network_throughput_pm_qos = { .requests = PLIST_HEAD_INIT(network_throughput_pm_qos.requests, pm_qos_lock), .notifiers = &network_throughput_notifier, .name = "network_throughput", - .default_value = 0, + .target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE, + .default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE, .type = PM_QOS_MAX, }; @@ -132,6 +136,16 @@ static inline int pm_qos_get_value(struct pm_qos_object *o) } } +static inline s32 pm_qos_read_value(struct pm_qos_object *o) +{ + return o->target_value; +} + +static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value) +{ + o->value = target_value; +} + static void update_target(struct pm_qos_object *o, struct plist_node *node, int del, int value) { @@ -156,6 +170,7 @@ static void update_target(struct pm_qos_object *o, struct plist_node *node, plist_add(node, &o->requests); } curr_value = pm_qos_get_value(o); + pm_qos_set_value(o, curr_value); spin_unlock_irqrestore(&pm_qos_lock, flags); if (prev_value != curr_value) @@ -190,18 +205,11 @@ static int find_pm_qos_object_by_minor(int minor) * pm_qos_request - returns current system wide qos expectation * @pm_qos_class: identification of which qos value is requested * - * This function returns the current target value in an atomic manner. + * This function returns the current target value. */ int pm_qos_request(int pm_qos_class) { - unsigned long flags; - int value; - - spin_lock_irqsave(&pm_qos_lock, flags); - value = pm_qos_get_value(pm_qos_array[pm_qos_class]); - spin_unlock_irqrestore(&pm_qos_lock, flags); - - return value; + return pm_qos_read_value(pm_qos_array[pm_qos_class]); } EXPORT_SYMBOL_GPL(pm_qos_request); -- 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/