tools: create power/x86/x86_energy_perf_policy
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 the
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.
See x86_energy_perf_policy.8 man page for more information.
Background:
Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate
if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS,
without actually modifying the MSR.
In March, 2010, 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".
In June, 2010, I proposed a generic user/kernel API to
generalize 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, 2010, 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 that same utility, after responding to some review feedback,
to live in tools/power/, where it is easily found.
Signed-off-by: Len Brown <len.brown@intel.com>
2010-10-23 03:53:03 +00:00
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/*
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* x86_energy_perf_policy -- set the energy versus performance
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* policy preference bias on recent X86 processors.
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*/
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/*
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* Copyright (c) 2010, Intel Corporation.
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* Len Brown <len.brown@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/resource.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <sys/time.h>
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#include <stdlib.h>
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#include <string.h>
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unsigned int verbose; /* set with -v */
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unsigned int read_only; /* set with -r */
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char *progname;
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unsigned long long new_bias;
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int cpu = -1;
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/*
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* Usage:
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*
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* -c cpu: limit action to a single CPU (default is all CPUs)
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* -v: verbose output (can invoke more than once)
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* -r: read-only, don't change any settings
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*
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* performance
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* Performance is paramount.
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2011-03-31 01:57:33 +00:00
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* Unwilling to sacrifice any performance
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tools: create power/x86/x86_energy_perf_policy
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 the
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.
See x86_energy_perf_policy.8 man page for more information.
Background:
Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate
if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS,
without actually modifying the MSR.
In March, 2010, 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".
In June, 2010, I proposed a generic user/kernel API to
generalize 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, 2010, 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 that same utility, after responding to some review feedback,
to live in tools/power/, where it is easily found.
Signed-off-by: Len Brown <len.brown@intel.com>
2010-10-23 03:53:03 +00:00
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* for the sake of energy saving. (hardware default)
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*
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* normal
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* Can tolerate minor performance compromise
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* for potentially significant energy savings.
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* (reasonable default for most desktops and servers)
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*
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* powersave
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* Can tolerate significant performance hit
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* to maximize energy savings.
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*
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* n
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* a numerical value to write to the underlying MSR.
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*/
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void usage(void)
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{
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printf("%s: [-c cpu] [-v] "
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"(-r | 'performance' | 'normal' | 'powersave' | n)\n",
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progname);
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exit(1);
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}
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#define MSR_IA32_ENERGY_PERF_BIAS 0x000001b0
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#define BIAS_PERFORMANCE 0
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#define BIAS_BALANCE 6
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#define BIAS_POWERSAVE 15
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void cmdline(int argc, char **argv)
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{
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int opt;
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progname = argv[0];
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while ((opt = getopt(argc, argv, "+rvc:")) != -1) {
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switch (opt) {
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case 'c':
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cpu = atoi(optarg);
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break;
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case 'r':
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read_only = 1;
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break;
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case 'v':
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verbose++;
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break;
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default:
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usage();
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}
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}
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/* if -r, then should be no additional optind */
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if (read_only && (argc > optind))
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usage();
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/*
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* if no -r , then must be one additional optind
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*/
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if (!read_only) {
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if (argc != optind + 1) {
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printf("must supply -r or policy param\n");
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usage();
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}
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if (!strcmp("performance", argv[optind])) {
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new_bias = BIAS_PERFORMANCE;
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} else if (!strcmp("normal", argv[optind])) {
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new_bias = BIAS_BALANCE;
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} else if (!strcmp("powersave", argv[optind])) {
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new_bias = BIAS_POWERSAVE;
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} else {
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char *endptr;
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new_bias = strtoull(argv[optind], &endptr, 0);
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if (endptr == argv[optind] ||
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new_bias > BIAS_POWERSAVE) {
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fprintf(stderr, "invalid value: %s\n",
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argv[optind]);
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usage();
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}
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}
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}
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}
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/*
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* validate_cpuid()
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* returns on success, quietly exits on failure (make verbose with -v)
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*/
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void validate_cpuid(void)
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{
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unsigned int eax, ebx, ecx, edx, max_level;
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unsigned int fms, family, model, stepping;
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eax = ebx = ecx = edx = 0;
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asm("cpuid" : "=a" (max_level), "=b" (ebx), "=c" (ecx),
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"=d" (edx) : "a" (0));
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if (ebx != 0x756e6547 || edx != 0x49656e69 || ecx != 0x6c65746e) {
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if (verbose)
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fprintf(stderr, "%.4s%.4s%.4s != GenuineIntel",
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(char *)&ebx, (char *)&edx, (char *)&ecx);
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exit(1);
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}
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asm("cpuid" : "=a" (fms), "=c" (ecx), "=d" (edx) : "a" (1) : "ebx");
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family = (fms >> 8) & 0xf;
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model = (fms >> 4) & 0xf;
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stepping = fms & 0xf;
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if (family == 6 || family == 0xf)
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model += ((fms >> 16) & 0xf) << 4;
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if (verbose > 1)
|
2011-07-16 03:39:00 +00:00
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printf("CPUID %d levels family:model:stepping "
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"0x%x:%x:%x (%d:%d:%d)\n", max_level,
|
tools: create power/x86/x86_energy_perf_policy
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 the
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.
See x86_energy_perf_policy.8 man page for more information.
Background:
Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate
if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS,
without actually modifying the MSR.
In March, 2010, 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".
In June, 2010, I proposed a generic user/kernel API to
generalize 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, 2010, 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 that same utility, after responding to some review feedback,
to live in tools/power/, where it is easily found.
Signed-off-by: Len Brown <len.brown@intel.com>
2010-10-23 03:53:03 +00:00
|
|
|
family, model, stepping, family, model, stepping);
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if (!(edx & (1 << 5))) {
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if (verbose)
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printf("CPUID: no MSR\n");
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exit(1);
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}
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/*
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* Support for MSR_IA32_ENERGY_PERF_BIAS
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* is indicated by CPUID.06H.ECX.bit3
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|
*/
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asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (6));
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if (verbose)
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printf("CPUID.06H.ECX: 0x%x\n", ecx);
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if (!(ecx & (1 << 3))) {
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if (verbose)
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printf("CPUID: No MSR_IA32_ENERGY_PERF_BIAS\n");
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exit(1);
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}
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|
return; /* success */
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|
}
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|
unsigned long long get_msr(int cpu, int offset)
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|
{
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|
unsigned long long msr;
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|
char msr_path[32];
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|
|
int retval;
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int fd;
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sprintf(msr_path, "/dev/cpu/%d/msr", cpu);
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fd = open(msr_path, O_RDONLY);
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|
if (fd < 0) {
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|
printf("Try \"# modprobe msr\"\n");
|
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|
perror(msr_path);
|
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|
|
exit(1);
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|
}
|
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|
retval = pread(fd, &msr, sizeof msr, offset);
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|
if (retval != sizeof msr) {
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|
printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval);
|
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|
|
exit(-2);
|
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|
|
}
|
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|
close(fd);
|
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|
|
return msr;
|
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|
|
}
|
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|
unsigned long long put_msr(int cpu, unsigned long long new_msr, int offset)
|
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|
|
{
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|
|
unsigned long long old_msr;
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|
|
char msr_path[32];
|
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|
|
int retval;
|
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|
|
int fd;
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|
sprintf(msr_path, "/dev/cpu/%d/msr", cpu);
|
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|
fd = open(msr_path, O_RDWR);
|
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|
|
if (fd < 0) {
|
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|
|
perror(msr_path);
|
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|
|
exit(1);
|
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|
|
}
|
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|
|
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|
|
|
retval = pread(fd, &old_msr, sizeof old_msr, offset);
|
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|
|
if (retval != sizeof old_msr) {
|
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|
|
perror("pwrite");
|
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|
|
printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval);
|
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|
|
exit(-2);
|
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|
|
}
|
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|
|
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|
|
|
retval = pwrite(fd, &new_msr, sizeof new_msr, offset);
|
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|
|
if (retval != sizeof new_msr) {
|
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|
|
perror("pwrite");
|
|
|
|
printf("pwrite cpu%d 0x%x = %d\n", cpu, offset, retval);
|
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|
|
exit(-2);
|
|
|
|
}
|
|
|
|
|
|
|
|
close(fd);
|
|
|
|
|
|
|
|
return old_msr;
|
|
|
|
}
|
|
|
|
|
|
|
|
void print_msr(int cpu)
|
|
|
|
{
|
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|
|
printf("cpu%d: 0x%016llx\n",
|
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|
|
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)
|
2012-11-15 19:02:00 +00:00
|
|
|
break;
|
tools: create power/x86/x86_energy_perf_policy
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 the
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.
See x86_energy_perf_policy.8 man page for more information.
Background:
Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate
if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS,
without actually modifying the MSR.
In March, 2010, 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".
In June, 2010, I proposed a generic user/kernel API to
generalize 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, 2010, 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 that same utility, after responding to some review feedback,
to live in tools/power/, where it is easily found.
Signed-off-by: Len Brown <len.brown@intel.com>
2010-10-23 03:53:03 +00:00
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func(cpu);
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}
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fclose(fp);
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}
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int main(int argc, char **argv)
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{
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cmdline(argc, argv);
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if (verbose > 1)
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printf("x86_energy_perf_policy Nov 24, 2010"
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" - Len Brown <lenb@kernel.org>\n");
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if (verbose > 1 && !read_only)
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printf("new_bias %lld\n", new_bias);
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validate_cpuid();
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if (cpu != -1) {
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if (read_only)
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print_msr(cpu);
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else
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update_msr(cpu);
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} else {
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if (read_only)
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for_every_cpu(print_msr);
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else
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for_every_cpu(update_msr);
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}
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return 0;
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}
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