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Linux/tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c

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  1 /*
  2  * x86_energy_perf_policy -- set the energy versus performance
  3  * policy preference bias on recent X86 processors.
  4  */
  5 /*
  6  * Copyright (c) 2010, Intel Corporation.
  7  * Len Brown <len.brown@intel.com>
  8  *
  9  * This program is free software; you can redistribute it and/or modify it
 10  * under the terms and conditions of the GNU General Public License,
 11  * version 2, as published by the Free Software Foundation.
 12  *
 13  * This program is distributed in the hope it will be useful, but WITHOUT
 14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 16  * more details.
 17  *
 18  * You should have received a copy of the GNU General Public License along with
 19  * this program; if not, write to the Free Software Foundation, Inc.,
 20  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 21  */
 22 
 23 #include <stdio.h>
 24 #include <unistd.h>
 25 #include <sys/types.h>
 26 #include <sys/stat.h>
 27 #include <sys/resource.h>
 28 #include <fcntl.h>
 29 #include <signal.h>
 30 #include <sys/time.h>
 31 #include <stdlib.h>
 32 #include <string.h>
 33 
 34 unsigned int verbose;           /* set with -v */
 35 unsigned int read_only;         /* set with -r */
 36 char *progname;
 37 unsigned long long new_bias;
 38 int cpu = -1;
 39 
 40 /*
 41  * Usage:
 42  *
 43  * -c cpu: limit action to a single CPU (default is all CPUs)
 44  * -v: verbose output (can invoke more than once)
 45  * -r: read-only, don't change any settings
 46  *
 47  *  performance
 48  *      Performance is paramount.
 49  *      Unwilling to sacrifice any performance
 50  *      for the sake of energy saving. (hardware default)
 51  *
 52  *  normal
 53  *      Can tolerate minor performance compromise
 54  *      for potentially significant energy savings.
 55  *      (reasonable default for most desktops and servers)
 56  *
 57  *  powersave
 58  *      Can tolerate significant performance hit
 59  *      to maximize energy savings.
 60  *
 61  * n
 62  *      a numerical value to write to the underlying MSR.
 63  */
 64 void usage(void)
 65 {
 66         printf("%s: [-c cpu] [-v] "
 67                 "(-r | 'performance' | 'normal' | 'powersave' | n)\n",
 68                 progname);
 69         exit(1);
 70 }
 71 
 72 #define MSR_IA32_ENERGY_PERF_BIAS       0x000001b0
 73 
 74 #define BIAS_PERFORMANCE                0
 75 #define BIAS_BALANCE                    6
 76 #define BIAS_POWERSAVE                  15
 77 
 78 void cmdline(int argc, char **argv)
 79 {
 80         int opt;
 81 
 82         progname = argv[0];
 83 
 84         while ((opt = getopt(argc, argv, "+rvc:")) != -1) {
 85                 switch (opt) {
 86                 case 'c':
 87                         cpu = atoi(optarg);
 88                         break;
 89                 case 'r':
 90                         read_only = 1;
 91                         break;
 92                 case 'v':
 93                         verbose++;
 94                         break;
 95                 default:
 96                         usage();
 97                 }
 98         }
 99         /* if -r, then should be no additional optind */
100         if (read_only && (argc > optind))
101                 usage();
102 
103         /*
104          * if no -r , then must be one additional optind
105          */
106         if (!read_only) {
107 
108                 if (argc != optind + 1) {
109                         printf("must supply -r or policy param\n");
110                         usage();
111                         }
112 
113                 if (!strcmp("performance", argv[optind])) {
114                         new_bias = BIAS_PERFORMANCE;
115                 } else if (!strcmp("normal", argv[optind])) {
116                         new_bias = BIAS_BALANCE;
117                 } else if (!strcmp("powersave", argv[optind])) {
118                         new_bias = BIAS_POWERSAVE;
119                 } else {
120                         char *endptr;
121 
122                         new_bias = strtoull(argv[optind], &endptr, 0);
123                         if (endptr == argv[optind] ||
124                                 new_bias > BIAS_POWERSAVE) {
125                                         fprintf(stderr, "invalid value: %s\n",
126                                                 argv[optind]);
127                                 usage();
128                         }
129                 }
130         }
131 }
132 
133 /*
134  * validate_cpuid()
135  * returns on success, quietly exits on failure (make verbose with -v)
136  */
137 void validate_cpuid(void)
138 {
139         unsigned int eax, ebx, ecx, edx, max_level;
140         unsigned int fms, family, model, stepping;
141 
142         eax = ebx = ecx = edx = 0;
143 
144         asm("cpuid" : "=a" (max_level), "=b" (ebx), "=c" (ecx),
145                 "=d" (edx) : "a" (0));
146 
147         if (ebx != 0x756e6547 || edx != 0x49656e69 || ecx != 0x6c65746e) {
148                 if (verbose)
149                         fprintf(stderr, "%.4s%.4s%.4s != GenuineIntel",
150                                 (char *)&ebx, (char *)&edx, (char *)&ecx);
151                 exit(1);
152         }
153 
154         asm("cpuid" : "=a" (fms), "=c" (ecx), "=d" (edx) : "a" (1) : "ebx");
155         family = (fms >> 8) & 0xf;
156         model = (fms >> 4) & 0xf;
157         stepping = fms & 0xf;
158         if (family == 6 || family == 0xf)
159                 model += ((fms >> 16) & 0xf) << 4;
160 
161         if (verbose > 1)
162                 printf("CPUID %d levels family:model:stepping "
163                         "0x%x:%x:%x (%d:%d:%d)\n", max_level,
164                         family, model, stepping, family, model, stepping);
165 
166         if (!(edx & (1 << 5))) {
167                 if (verbose)
168                         printf("CPUID: no MSR\n");
169                 exit(1);
170         }
171 
172         /*
173          * Support for MSR_IA32_ENERGY_PERF_BIAS
174          * is indicated by CPUID.06H.ECX.bit3
175          */
176         asm("cpuid" : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx) : "a" (6));
177         if (verbose)
178                 printf("CPUID.06H.ECX: 0x%x\n", ecx);
179         if (!(ecx & (1 << 3))) {
180                 if (verbose)
181                         printf("CPUID: No MSR_IA32_ENERGY_PERF_BIAS\n");
182                 exit(1);
183         }
184         return; /* success */
185 }
186 
187 unsigned long long get_msr(int cpu, int offset)
188 {
189         unsigned long long msr;
190         char msr_path[32];
191         int retval;
192         int fd;
193 
194         sprintf(msr_path, "/dev/cpu/%d/msr", cpu);
195         fd = open(msr_path, O_RDONLY);
196         if (fd < 0) {
197                 printf("Try \"# modprobe msr\"\n");
198                 perror(msr_path);
199                 exit(1);
200         }
201 
202         retval = pread(fd, &msr, sizeof msr, offset);
203 
204         if (retval != sizeof msr) {
205                 printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval);
206                 exit(-2);
207         }
208         close(fd);
209         return msr;
210 }
211 
212 unsigned long long  put_msr(int cpu, unsigned long long new_msr, int offset)
213 {
214         unsigned long long old_msr;
215         char msr_path[32];
216         int retval;
217         int fd;
218 
219         sprintf(msr_path, "/dev/cpu/%d/msr", cpu);
220         fd = open(msr_path, O_RDWR);
221         if (fd < 0) {
222                 perror(msr_path);
223                 exit(1);
224         }
225 
226         retval = pread(fd, &old_msr, sizeof old_msr, offset);
227         if (retval != sizeof old_msr) {
228                 perror("pwrite");
229                 printf("pread cpu%d 0x%x = %d\n", cpu, offset, retval);
230                 exit(-2);
231         }
232 
233         retval = pwrite(fd, &new_msr, sizeof new_msr, offset);
234         if (retval != sizeof new_msr) {
235                 perror("pwrite");
236                 printf("pwrite cpu%d 0x%x = %d\n", cpu, offset, retval);
237                 exit(-2);
238         }
239 
240         close(fd);
241 
242         return old_msr;
243 }
244 
245 void print_msr(int cpu)
246 {
247         printf("cpu%d: 0x%016llx\n",
248                 cpu, get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS));
249 }
250 
251 void update_msr(int cpu)
252 {
253         unsigned long long previous_msr;
254 
255         previous_msr = put_msr(cpu, new_bias, MSR_IA32_ENERGY_PERF_BIAS);
256 
257         if (verbose)
258                 printf("cpu%d  msr0x%x 0x%016llx -> 0x%016llx\n",
259                         cpu, MSR_IA32_ENERGY_PERF_BIAS, previous_msr, new_bias);
260 
261         return;
262 }
263 
264 char *proc_stat = "/proc/stat";
265 /*
266  * run func() on every cpu in /dev/cpu
267  */
268 void for_every_cpu(void (func)(int))
269 {
270         FILE *fp;
271         int retval;
272 
273         fp = fopen(proc_stat, "r");
274         if (fp == NULL) {
275                 perror(proc_stat);
276                 exit(1);
277         }
278 
279         retval = fscanf(fp, "cpu %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d\n");
280         if (retval != 0) {
281                 perror("/proc/stat format");
282                 exit(1);
283         }
284 
285         while (1) {
286                 int cpu;
287 
288                 retval = fscanf(fp,
289                         "cpu%u %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d\n",
290                         &cpu);
291                 if (retval != 1)
292                         break;
293 
294                 func(cpu);
295         }
296         fclose(fp);
297 }
298 
299 int main(int argc, char **argv)
300 {
301         cmdline(argc, argv);
302 
303         if (verbose > 1)
304                 printf("x86_energy_perf_policy Nov 24, 2010"
305                                 " - Len Brown <lenb@kernel.org>\n");
306         if (verbose > 1 && !read_only)
307                 printf("new_bias %lld\n", new_bias);
308 
309         validate_cpuid();
310 
311         if (cpu != -1) {
312                 if (read_only)
313                         print_msr(cpu);
314                 else
315                         update_msr(cpu);
316         } else {
317                 if (read_only)
318                         for_every_cpu(print_msr);
319                 else
320                         for_every_cpu(update_msr);
321         }
322 
323         return 0;
324 }
325 

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