Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753653AbbHaO7d (ORCPT ); Mon, 31 Aug 2015 10:59:33 -0400 Received: from casper.infradead.org ([85.118.1.10]:41390 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752858AbbHaO7b (ORCPT ); Mon, 31 Aug 2015 10:59:31 -0400 Date: Mon, 31 Aug 2015 16:59:24 +0200 From: Peter Zijlstra To: Huang Rui Cc: Borislav Petkov , Jean Delvare , Guenter Roeck , Andy Lutomirski , Andreas Herrmann , Thomas Gleixner , Ingo Molnar , "Rafael J. Wysocki" , Len Brown , John Stultz , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, x86@kernel.org, Andreas Herrmann , Aravind Gopalakrishnan , Borislav Petkov , Fengguang Wu , Aaron Lu , Tony Li Subject: Re: [PATCH 12/15] hwmon, fam15h_power: introduce a cpu accumulated power reporting algorithm Message-ID: <20150831145924.GL18673@twins.programming.kicks-ass.net> References: <1440662866-28716-1-git-send-email-ray.huang@amd.com> <1440662866-28716-13-git-send-email-ray.huang@amd.com> <20150831132535.GK19282@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150831132535.GK19282@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2411 Lines: 62 On Mon, Aug 31, 2015 at 03:25:35PM +0200, Peter Zijlstra wrote: > On Thu, Aug 27, 2015 at 04:07:43PM +0800, Huang Rui wrote: > > +static ssize_t show_power_acc(struct device *dev, > > + struct device_attribute *attr, char *buf) > > +{ > > + int cpu, cu, cu_num, cores_per_cu; > > + u64 curr_cu_acc_power[MAX_CUS], > > + curr_ptsc[MAX_CUS], jdelta[MAX_CUS]; > > + u64 tdelta, avg_acc; > > + struct fam15h_power_data *data = dev_get_drvdata(dev); > > + > > + cores_per_cu = amd_get_cores_per_cu(); > > + cu_num = boot_cpu_data.x86_max_cores / cores_per_cu; > > + > > + for (cpu = 0, avg_acc = 0; cpu < cu_num * cores_per_cu; cpu += cores_per_cu) { > > + cu = cpu / cores_per_cu; > > + if (rdmsrl_safe_on_cpu(cpu, MSR_F15H_PTSC, &curr_ptsc[cu])) { > > + pr_err("Failed to read PTSC counter MSR on core%d\n", > > + cpu); > > + return 0; > > + } > > + > > + if (rdmsrl_safe_on_cpu(cpu, MSR_F15H_CU_PWR_ACCUMULATOR, > > + &curr_cu_acc_power[cu])) { > > + pr_err("Failed to read compute unit power accumulator MSR on core%d\n", > > + cpu); > > + return 0; > > + } > > + > > + if (curr_cu_acc_power[cu] < data->cu_acc_power[cu]) { > > + jdelta[cu] = data->max_cu_acc_power + curr_cu_acc_power[cu]; > > + jdelta[cu] -= data->cu_acc_power[cu]; > > + } else { > > + jdelta[cu] = curr_cu_acc_power[cu] - data->cu_acc_power[cu]; > > + } > > + tdelta = curr_ptsc[cu] - data->cpu_sw_pwr_ptsc[cu]; > > + jdelta[cu] *= data->cpu_pwr_sample_ratio * 1000; > > + do_div(jdelta[cu], tdelta); > > + > > + mutex_lock(&data->acc_pwr_mutex); > > + data->cu_acc_power[cu] = curr_cu_acc_power[cu]; > > + data->cpu_sw_pwr_ptsc[cu] = curr_ptsc[cu]; > > + mutex_unlock(&data->acc_pwr_mutex); > > + > > + /* the unit is microWatt */ > > + avg_acc += jdelta[cu]; > > + } > > + > > + return sprintf(buf, "%u\n", (unsigned int) avg_acc); > > +} > > +static DEVICE_ATTR(power1_acc, S_IRUGO, show_power_acc, NULL); > > This is a world readable file that sprays IPIs across the entire system, > how is that a good idea? FWIW this driver is also hotplug challenged. Not to mention it relies on cpu number layout in unhealthy ways. -- 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/