ä 11/25/2010 1:52 PM, Chen Gong åé: > ä 11/24/2010 1:31 PM, Len Brown åé: >> From: Len Brown<len.brown@xxxxxxxxx> >> >> MSR_IA32_ENERGY_PERF_BIAS first became available on Westmere Xeon. >> It is implemented in all Sandy Bridge processors -- mobile, desktop >> and server. >> It is expected to become increasingly important in subsequent >> generations. >> >> x86_energy_perf_policy is a user-space utility to set this >> hardware energy vs performance policy hint in the processor. >> Most systems would benefit from "x86_energy_perf_policy normal" >> at system startup, as the hardware default is maximum performance >> at the expense of energy efficiency. >> >> Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate >> if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS, >> though the kernel does not actually program the MSR. >> >> In March, Venkatesh Pallipadi proposed a small driver >> that programmed MSR_IA32_ENERGY_PERF_BIAS, based on >> the cpufreq governor in use. It also offered >> a boot-time cmdline option to override. >> http://lkml.org/lkml/2010/3/4/457 >> But hiding the hardware policy behind the >> governor choice was deemed "kinda icky". >> >> So in June, I proposed a generic user/kernel API to >> consolidate the power/performance policy trade-off. >> "RFC: /sys/power/policy_preference" >> http://lkml.org/lkml/2010/6/16/399 >> That is my preference for implementing this capability, >> but I received no support on the list. >> >> So in September, I sent x86_energy_perf_policy.c to LKML, >> a user-space utility that scribbles directly to the MSR. >> http://lkml.org/lkml/2010/9/28/246 >> >> Here is the same utility re-sent, this time proposed >> to reside in the kernel tools directory. >> >> Signed-off-by: Len Brown<len.brown@xxxxxxxxx> >> --- >> v2 >> create man page >> minor tweaks in response to review comments >> >> tools/power/x86/x86_energy_perf_policy/Makefile | 8 + >> .../x86_energy_perf_policy.8 | 104 +++++++ >> .../x86_energy_perf_policy.c | 325 ++++++++++++++++++++ >> >> diff --git a/tools/power/x86/x86_energy_perf_policy/Makefile >> b/tools/power/x86/x86_energy_perf_policy/Makefile >> new file mode 100644 >> index 0000000..f458237 >> --- /dev/null >> +++ b/tools/power/x86/x86_energy_perf_policy/Makefile >> @@ -0,0 +1,8 @@ >> +x86_energy_perf_policy : x86_energy_perf_policy.c >> + >> +clean : >> + rm -f x86_energy_perf_policy >> + >> +install : >> + install x86_energy_perf_policy /usr/bin/ >> + install x86_energy_perf_policy.8 /usr/share/man/man8/ >> diff --git >> a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.8 >> b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.8 >> new file mode 100644 >> index 0000000..8eaaad6 >> --- /dev/null >> +++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.8 >> @@ -0,0 +1,104 @@ >> +.\" This page Copyright (C) 2010 Len Brown<len.brown@xxxxxxxxx> >> +.\" Distributed under the GPL, Copyleft 1994. >> +.TH X86_ENERGY_PERF_POLICY 8 >> +.SH NAME >> +x86_energy_perf_policy \- read or write MSR_IA32_ENERGY_PERF_BIAS >> +.SH SYNOPSIS >> +.ft B >> +.B x86_energy_perf_policy >> +.RB [ "\-c cpu" ] >> +.RB [ "\-v" ] >> +.RB "\-r" >> +.br >> +.B x86_energy_perf_policy >> +.RB [ "\-c cpu" ] >> +.RB [ "\-v" ] >> +.RB 'performance' >> +.br >> +.B x86_energy_perf_policy >> +.RB [ "\-c cpu" ] >> +.RB [ "\-v" ] >> +.RB 'normal' >> +.br >> +.B x86_energy_perf_policy >> +.RB [ "\-c cpu" ] >> +.RB [ "\-v" ] >> +.RB 'powersave' >> +.br >> +.B x86_energy_perf_policy >> +.RB [ "\-c cpu" ] >> +.RB [ "\-v" ] >> +.RB n >> +.br >> +.SH DESCRIPTION >> +\fBx86_energy_perf_policy\fP >> +allows software to convey >> +its policy for the relative importance of performance >> +versus energy savings to the processor. >> + >> +The processor uses this information in model-specific ways >> +when it must select trade-offs between performance and >> +energy efficiency. >> + >> +This policy hint does not supersede Processor Performance states >> +(P-states) or CPU Idle power states (C-states), but allows >> +software to have influence where it would otherwise be unable >> +to express a preference. >> + >> +For example, this setting may tell the hardware how >> +aggressively or conservatively to control frequency >> +in the "turbo range" above the explicitly OS-controlled >> +P-state frequency range. It may also tell the hardware >> +how aggressively is should enter the OS requested C-states. >> + >> +Support for this feature is indicated by CPUID.06H.ECX.bit3 >> +per the Intel Architectures Software Developer's Manual. >> + >> +.SS Options >> +\fB-c\fP limits operation to a single CPU. >> +The default is to operate on all CPUs. >> +Note that MSR_IA32_ENERGY_PERF_BIAS is defined per >> +logical processor, but that the initial implementations >> +of the MSR were shared among all processors in each package. >> +.PP >> +\fB-v\fP increases verbosity. By default >> +x86_energy_perf_policy is silent. >> +.PP >> +\fB-r\fP is for "read-only" mode - the unchanged state >> +is read and displayed. >> +.PP >> +.I performance >> +Set a policy where performance is paramount. >> +The processor will be unwilling to sacrifice any performance >> +for the sake of energy saving. This is the hardware default. >> +.PP >> +.I normal >> +Set a policy with a normal balance between performance and energy >> efficiency. >> +The processor will tolerate minor performance compromise >> +for potentially significant energy savings. >> +This reasonable default for most desktops and servers. >> +.PP >> +.I powersave >> +Set a policy where the processor can accept >> +a measurable performance hit to maximize energy efficiency. >> +.PP >> +.I n >> +Set MSR_IA32_ENERGY_PERF_BIAS to the specified number. >> +The range of valid numbers is 0-15, where 0 is maximum >> +performance and 15 is maximum energy efficiency. >> + >> +.SH NOTES >> +.B "x86_energy_perf_policy " >> +runs only as root. >> +.SH FILES >> +.ta >> +.nf >> +/dev/cpu/*/msr >> +.fi >> + >> +.SH "SEE ALSO" >> +msr(4) >> +.PP >> +.SH AUTHORS >> +.nf >> +Written by Len Brown<len.brown@xxxxxxxxx> >> diff --git >> a/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c >> b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c >> new file mode 100644 >> index 0000000..b539923 >> --- /dev/null >> +++ b/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c >> @@ -0,0 +1,325 @@ >> +/* >> + * x86_energy_perf_policy -- set the energy versus performance >> + * policy preference bias on recent X86 processors. >> + */ >> +/* >> + * Copyright (c) 2010, Intel Corporation. >> + * Len Brown<len.brown@xxxxxxxxx> >> + * >> + * This program is free software; you can redistribute it and/or >> modify it >> + * under the terms and conditions of the GNU General Public License, >> + * version 2, as published by the Free Software Foundation. >> + * >> + * This program is distributed in the hope it will be useful, but >> WITHOUT >> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or >> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public >> License for >> + * more details. >> + * >> + * You should have received a copy of the GNU General Public License >> along with >> + * this program; if not, write to the Free Software Foundation, Inc., >> + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. >> + */ >> + >> +#include<stdio.h> >> +#include<unistd.h> >> +#include<sys/types.h> >> +#include<sys/stat.h> >> +#include<sys/resource.h> >> +#include<fcntl.h> >> +#include<signal.h> >> +#include<sys/time.h> >> +#include<stdlib.h> >> +#include<string.h> >> + >> +unsigned int verbose; /* set with -v */ >> +unsigned int read_only; /* set with -r */ >> +char *progname; >> +unsigned long long new_bias; >> +int cpu = -1; >> + >> +/* >> + * Usage: >> + * >> + * -c cpu: limit action to a single CPU (default is all CPUs) >> + * -v: verbose output (can invoke more than once) >> + * -r: read-only, don't change any settings >> + * >> + * performance >> + * Performance is paramount. >> + * Unwilling to sacrafice any performance >> + * for the sake of energy saving. (hardware default) >> + * >> + * normal >> + * Can tolerate minor performance compromise >> + * for potentially significant energy savings. >> + * (reasonable default for most desktops and servers) >> + * >> + * powersave >> + * Can tolerate significant performance hit >> + * to maximize energy savings. >> + * >> + * n >> + * a numerical value to write to the underlying MSR. >> + */ >> +void usage(void) >> +{ >> + printf("%s: [-c cpu] [-v] " >> + "(-r | 'performance' | 'normal' | 'powersave' | n)\n", >> + progname); >> + exit(1); >> +} >> + >> +#define MSR_IA32_ENERGY_PERF_BIAS 0x000001b0 >> + >> +#define BIAS_PERFORMANCE 0 >> +#define BIAS_BALANCE 6 >> +#define BIAS_POWERSAVE 15 >> + >> +void cmdline(int argc, char **argv) >> +{ >> + int opt; >> + >> + progname = argv[0]; >> + >> + while ((opt = getopt(argc, argv, "+rvc:")) != -1) { >> + switch (opt) { >> + case 'c': >> + cpu = atoi(optarg); >> + break; >> + case 'r': >> + read_only = 1; >> + break; >> + case 'v': >> + verbose++; >> + break; >> + default: >> + usage(); >> + } >> + } >> + /* if -r, then should be no additional optind */ >> + if (read_only&& (argc> optind)) >> + usage(); >> + >> + /* >> + * if no -r , then must be one additional optind >> + */ >> + if (!read_only) { >> + >> + if (argc != optind + 1) { >> + printf("must supply -r or policy param\n"); >> + usage(); >> + } >> + >> + if (!strcmp("performance", argv[optind])) { >> + new_bias = BIAS_PERFORMANCE; >> + } else if (!strcmp("normal", argv[optind])) { >> + new_bias = BIAS_BALANCE; >> + } else if (!strcmp("powersave", argv[optind])) { >> + new_bias = BIAS_POWERSAVE; >> + } else { >> + char *endptr; >> + >> + new_bias = strtoull(argv[optind],&endptr, 0); >> + if (endptr == argv[optind] || >> + new_bias> BIAS_POWERSAVE) { >> + fprintf(stderr, "invalid value: %s\n", >> + argv[optind]); >> + usage(); >> + } >> + } >> + } >> +} >> + >> +/* >> + * validate_cpuid() >> + * returns on success, quietly exits on failure (make verbose with -v) >> + */ >> +void validate_cpuid(void) >> +{ >> + unsigned int eax, ebx, ecx, edx, max_level; >> + char brand[16]; >> + unsigned int fms, family, model, stepping; >> + >> + eax = ebx = ecx = edx = 0; >> + >> + asm("cpuid" : "=a" (max_level), "=b" (ebx), "=c" (ecx), >> + "=d" (edx) : "a" (0)); >> + >> + if (ebx != 0x756e6547 || edx != 0x49656e69 || ecx != 0x6c65746e) { >> + if (verbose) >> + fprintf(stderr, "%.4s%.4s%.4s != GenuineIntel", >> + (char *)&ebx, (char *)&edx, (char *)&ecx); >> + exit(1); >> + } >> + >> + asm("cpuid" : "=a" (fms), "=c" (ecx), "=d" (edx) : "a" (1) : "ebx"); >> + family = (fms>> 8)& 0xf; >> + model = (fms>> 4)& 0xf; >> + stepping = fms& 0xf; >> + if (family == 6 || family == 0xf) >> + model += ((fms>> 16)& 0xf)<< 4; >> + >> + if (verbose> 1) >> + printf("CPUID %s %d levels family:model:stepping " >> + "0x%x:%x:%x (%d:%d:%d)\n", brand, max_level, >> + family, model, stepping, family, model, stepping); >> + >> + if (!(edx& (1<< 5))) { >> + if (verbose) >> + printf("CPUID: no MSR\n"); >> + exit(1); >> + } >> + >> + /* >> + * Support for MSR_IA32_ENERGY_PERF_BIAS >> + * is indicated by CPUID.06H.ECX.bit3 >> + */ >> + asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" >> (6)); >> + if (verbose) >> + printf("CPUID.06H.ECX: 0x%x\n", ecx); >> + if (!(ecx& (1<< 3))) { >> + if (verbose) >> + printf("CPUID: No MSR_IA32_ENERGY_PERF_BIAS\n"); >> + exit(1); >> + } >> + return; /* success */ >> +} >> + >> +unsigned long long get_msr(int cpu, int offset) >> +{ >> + unsigned long long msr; >> + char msr_path[32]; >> + int retval; >> + int fd; >> + >> + sprintf(msr_path, "/dev/cpu/%d/msr", cpu); >> + fd = open(msr_path, O_RDONLY); >> + if (fd< 0) { >> + printf("Try \"# modprobe msr\"\n"); >> + perror(msr_path); >> + exit(1); >> + } >> + >> + retval = pread(fd,&msr, sizeof msr, offset); >> + >> + if (retval != sizeof msr) { >> + printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval); >> + exit(-2); >> + } >> + close(fd); >> + return msr; >> +} >> + >> +unsigned long long put_msr(int cpu, unsigned long long new_msr, int >> offset) >> +{ >> + unsigned long long old_msr; >> + char msr_path[32]; >> + int retval; >> + int fd; >> + >> + sprintf(msr_path, "/dev/cpu/%d/msr", cpu); >> + fd = open(msr_path, O_RDWR); >> + if (fd< 0) { >> + perror(msr_path); >> + exit(1); >> + } >> + >> + retval = pread(fd,&old_msr, sizeof old_msr, offset); >> + if (retval != sizeof old_msr) { >> + perror("pwrite"); >> + printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval); >> + exit(-2); >> + } >> + >> + retval = pwrite(fd,&new_msr, sizeof new_msr, offset); >> + if (retval != sizeof new_msr) { >> + perror("pwrite"); >> + printf("pwrite cpu%d 0x%x = %d\n", cpu, offset, retval); >> + exit(-2); >> + } >> + >> + close(fd); >> + >> + return old_msr; >> +} >> + >> +void print_msr(int cpu) >> +{ >> + printf("cpu%d: 0x%016llx\n", >> + cpu, get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS)); >> +} >> + >> +void update_msr(int cpu) >> +{ >> + unsigned long long previous_msr; >> + >> + previous_msr = put_msr(cpu, new_bias, MSR_IA32_ENERGY_PERF_BIAS); >> + >> + if (verbose) >> + printf("cpu%d msr0x%x 0x%016llx -> 0x%016llx\n", >> + cpu, MSR_IA32_ENERGY_PERF_BIAS, previous_msr, new_bias); >> + >> + return; >> +} >> + >> +char *proc_stat = "/proc/stat"; >> +/* >> + * run func() on every cpu in /dev/cpu >> + */ >> +void for_every_cpu(void (func)(int)) >> +{ >> + FILE *fp; >> + int retval; >> + >> + fp = fopen(proc_stat, "r"); >> + if (fp == NULL) { >> + perror(proc_stat); >> + exit(1); >> + } >> + >> + retval = fscanf(fp, "cpu %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d\n"); >> + if (retval != 0) { >> + perror("/proc/stat format"); >> + exit(1); >> + } >> + >> + while (1) { >> + int cpu; >> + >> + retval = fscanf(fp, >> + "cpu%u %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d\n", >> + &cpu); >> + if (retval != 1) >> + return; >> + >> + func(cpu); >> + } >> + fclose(fp); >> +} >> + >> +int main(int argc, char **argv) >> +{ >> + cmdline(argc, argv); >> + >> + if (verbose> 1) >> + printf("x86_energy_perf_policy Nov 24, 2010" >> + " - Len Brown<lenb@xxxxxxxxxx>\n"); >> + if (verbose> 1&& !read_only) >> + printf("new_bias %lld\n", new_bias); >> + >> + validate_cpuid(); >> + >> + if (cpu != -1) { >> + if (read_only) >> + print_msr(cpu); >> + else >> + update_msr(cpu); >> + } else { >> + if (read_only) >> + for_every_cpu(print_msr); >> + else >> + for_every_cpu(update_msr); >> + } >> + >> + return 0; >> +} >> > I have 2 questions. > > 1. the usage looks too simple. If I haven't read the comments > in the source codes, I even can't know the exact meaning of these > parameters. Such as -v, -vv etc. How about adding the comments > as the part of the usage ? > > 2. the paramter "noraml | performance | powersave | n" looks weird. > why it can't look like other paramter (-r, -v etc.). For example, > I can't use it such as > "./x86_energy_perf_policy -c 0 normal -v" > -- One more question. From the spec, it should write 1 to the MSR 0x1FC[18] to enable this function after setting the Energy Policy on all threads in one package. _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
