Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935429AbcJQPtQ (ORCPT ); Mon, 17 Oct 2016 11:49:16 -0400 Received: from foss.arm.com ([217.140.101.70]:36850 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964858AbcJQPsK (ORCPT ); Mon, 17 Oct 2016 11:48:10 -0400 From: Juri Lelli To: linux-kernel@vger.kernel.org Cc: linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, peterz@infradead.org, vincent.guittot@linaro.org, robh+dt@kernel.org, mark.rutland@arm.com, linux@arm.linux.org.uk, sudeep.holla@arm.com, lorenzo.pieralisi@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, morten.rasmussen@arm.com, dietmar.eggemann@arm.com, juri.lelli@arm.com, broonie@kernel.org Subject: [PATCH v7 REPOST 8/9] arm: add sysfs cpu_capacity attribute Date: Mon, 17 Oct 2016 16:46:49 +0100 Message-Id: <20161017154650.18779-9-juri.lelli@arm.com> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20161017154650.18779-1-juri.lelli@arm.com> References: <20161017154650.18779-1-juri.lelli@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3269 Lines: 125 Add a sysfs cpu_capacity attribute with which it is possible to read and write (thus over-writing default values) CPUs capacity. This might be useful in situations where values needs changing after boot. The new attribute shows up as: /sys/devices/system/cpu/cpu*/cpu_capacity Cc: Russell King Signed-off-by: Juri Lelli --- Changes from v5: - add mutex to protect cpu_scale (as pointed out by Morten off-line) --- arch/arm/kernel/topology.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c index 18bb0474f7ec..46167bffbcf1 100644 --- a/arch/arm/kernel/topology.c +++ b/arch/arm/kernel/topology.c @@ -42,6 +42,7 @@ * updated during this sequence. */ static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE; +static DEFINE_MUTEX(cpu_scale_mutex); unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) { @@ -53,6 +54,76 @@ static void set_capacity_scale(unsigned int cpu, unsigned long capacity) per_cpu(cpu_scale, cpu) = capacity; } +#ifdef CONFIG_PROC_SYSCTL +#include +#include +static ssize_t show_cpu_capacity(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + ssize_t rc; + int cpunum = cpu->dev.id; + unsigned long capacity = arch_scale_cpu_capacity(NULL, cpunum); + + rc = sprintf(buf, "%lu\n", capacity); + + return rc; +} + +static ssize_t store_cpu_capacity(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + int this_cpu = cpu->dev.id, i; + unsigned long new_capacity; + ssize_t ret; + + if (count) { + char *p = (char *) buf; + + ret = kstrtoul(p, 0, &new_capacity); + if (ret) + return ret; + if (new_capacity > SCHED_CAPACITY_SCALE) + return -EINVAL; + + mutex_lock(&cpu_scale_mutex); + for_each_cpu(i, &cpu_topology[this_cpu].core_sibling) + set_capacity_scale(i, new_capacity); + mutex_unlock(&cpu_scale_mutex); + } + + return count; +} + +static DEVICE_ATTR(cpu_capacity, + 0644, + show_cpu_capacity, + store_cpu_capacity); + +static int register_cpu_capacity_sysctl(void) +{ + int i; + struct device *cpu; + + for_each_possible_cpu(i) { + cpu = get_cpu_device(i); + if (!cpu) { + pr_err("%s: too early to get CPU%d device!\n", + __func__, i); + continue; + } + device_create_file(cpu, &dev_attr_cpu_capacity); + } + + return 0; +} +late_initcall(register_cpu_capacity_sysctl); +#endif + #ifdef CONFIG_OF struct cpu_efficiency { const char *compatible; @@ -132,6 +203,7 @@ static void normalize_cpu_capacity(void) return; pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale); + mutex_lock(&cpu_scale_mutex); for_each_possible_cpu(cpu) { capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT) / capacity_scale; @@ -139,6 +211,7 @@ static void normalize_cpu_capacity(void) pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n", cpu, arch_scale_cpu_capacity(NULL, cpu)); } + mutex_unlock(&cpu_scale_mutex); } #ifdef CONFIG_CPU_FREQ -- 2.10.0