1 /*
2 * (C) 2010,2011 Thomas Renninger <trenn@suse.de>, Novell Inc.
3 *
4 * Licensed under the terms of the GNU GPL License version 2.
5 */
6
7 #if defined(__i386__) || defined(__x86_64__)
8
9 #include <stdio.h>
10 #include <stdint.h>
11 #include <stdlib.h>
12 #include <string.h>
13 #include <limits.h>
14
15 #include <cpufreq.h>
16
17 #include "helpers/helpers.h"
18 #include "idle_monitor/cpupower-monitor.h"
19
20 #define MSR_APERF 0xE8
21 #define MSR_MPERF 0xE7
22
23 #define MSR_TSC 0x10
24
25 #define MSR_AMD_HWCR 0xc0010015
26
27 enum mperf_id { C0 = 0, Cx, AVG_FREQ, MPERF_CSTATE_COUNT };
28
29 static int mperf_get_count_percent(unsigned int self_id, double *percent,
30 unsigned int cpu);
31 static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
32 unsigned int cpu);
33 static struct timespec time_start, time_end;
34
35 static cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = {
36 {
37 .name = "C0",
38 .desc = N_("Processor Core not idle"),
39 .id = C0,
40 .range = RANGE_THREAD,
41 .get_count_percent = mperf_get_count_percent,
42 },
43 {
44 .name = "Cx",
45 .desc = N_("Processor Core in an idle state"),
46 .id = Cx,
47 .range = RANGE_THREAD,
48 .get_count_percent = mperf_get_count_percent,
49 },
50
51 {
52 .name = "Freq",
53 .desc = N_("Average Frequency (including boost) in MHz"),
54 .id = AVG_FREQ,
55 .range = RANGE_THREAD,
56 .get_count = mperf_get_count_freq,
57 },
58 };
59
60 enum MAX_FREQ_MODE { MAX_FREQ_SYSFS, MAX_FREQ_TSC_REF };
61 static int max_freq_mode;
62 /*
63 * The max frequency mperf is ticking at (in C0), either retrieved via:
64 * 1) calculated after measurements if we know TSC ticks at mperf/P0 frequency
65 * 2) cpufreq /sys/devices/.../cpu0/cpufreq/cpuinfo_max_freq at init time
66 * 1. Is preferred as it also works without cpufreq subsystem (e.g. on Xen)
67 */
68 static unsigned long max_frequency;
69
70 static unsigned long long tsc_at_measure_start;
71 static unsigned long long tsc_at_measure_end;
72 static unsigned long long *mperf_previous_count;
73 static unsigned long long *aperf_previous_count;
74 static unsigned long long *mperf_current_count;
75 static unsigned long long *aperf_current_count;
76
77 /* valid flag for all CPUs. If a MSR read failed it will be zero */
78 static int *is_valid;
79
mperf_get_tsc(unsigned long long * tsc)80 static int mperf_get_tsc(unsigned long long *tsc)
81 {
82 int ret;
83 ret = read_msr(0, MSR_TSC, tsc);
84 if (ret)
85 dprint("Reading TSC MSR failed, returning %llu\n", *tsc);
86 return ret;
87 }
88
mperf_init_stats(unsigned int cpu)89 static int mperf_init_stats(unsigned int cpu)
90 {
91 unsigned long long val;
92 int ret;
93
94 ret = read_msr(cpu, MSR_APERF, &val);
95 aperf_previous_count[cpu] = val;
96 ret |= read_msr(cpu, MSR_MPERF, &val);
97 mperf_previous_count[cpu] = val;
98 is_valid[cpu] = !ret;
99
100 return 0;
101 }
102
mperf_measure_stats(unsigned int cpu)103 static int mperf_measure_stats(unsigned int cpu)
104 {
105 unsigned long long val;
106 int ret;
107
108 ret = read_msr(cpu, MSR_APERF, &val);
109 aperf_current_count[cpu] = val;
110 ret |= read_msr(cpu, MSR_MPERF, &val);
111 mperf_current_count[cpu] = val;
112 is_valid[cpu] = !ret;
113
114 return 0;
115 }
116
mperf_get_count_percent(unsigned int id,double * percent,unsigned int cpu)117 static int mperf_get_count_percent(unsigned int id, double *percent,
118 unsigned int cpu)
119 {
120 unsigned long long aperf_diff, mperf_diff, tsc_diff;
121 unsigned long long timediff;
122
123 if (!is_valid[cpu])
124 return -1;
125
126 if (id != C0 && id != Cx)
127 return -1;
128
129 mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
130 aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];
131
132 if (max_freq_mode == MAX_FREQ_TSC_REF) {
133 tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
134 *percent = 100.0 * mperf_diff / tsc_diff;
135 dprint("%s: TSC Ref - mperf_diff: %llu, tsc_diff: %llu\n",
136 mperf_cstates[id].name, mperf_diff, tsc_diff);
137 } else if (max_freq_mode == MAX_FREQ_SYSFS) {
138 timediff = timespec_diff_us(time_start, time_end);
139 *percent = 100.0 * mperf_diff / timediff;
140 dprint("%s: MAXFREQ - mperf_diff: %llu, time_diff: %llu\n",
141 mperf_cstates[id].name, mperf_diff, timediff);
142 } else
143 return -1;
144
145 if (id == Cx)
146 *percent = 100.0 - *percent;
147
148 dprint("%s: previous: %llu - current: %llu - (%u)\n",
149 mperf_cstates[id].name, mperf_diff, aperf_diff, cpu);
150 dprint("%s: %f\n", mperf_cstates[id].name, *percent);
151 return 0;
152 }
153
mperf_get_count_freq(unsigned int id,unsigned long long * count,unsigned int cpu)154 static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
155 unsigned int cpu)
156 {
157 unsigned long long aperf_diff, mperf_diff, time_diff, tsc_diff;
158
159 if (id != AVG_FREQ)
160 return 1;
161
162 if (!is_valid[cpu])
163 return -1;
164
165 mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
166 aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];
167
168 if (max_freq_mode == MAX_FREQ_TSC_REF) {
169 /* Calculate max_freq from TSC count */
170 tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
171 time_diff = timespec_diff_us(time_start, time_end);
172 max_frequency = tsc_diff / time_diff;
173 }
174
175 *count = max_frequency * ((double)aperf_diff / mperf_diff);
176 dprint("%s: Average freq based on %s maximum frequency:\n",
177 mperf_cstates[id].name,
178 (max_freq_mode == MAX_FREQ_TSC_REF) ? "TSC calculated" : "sysfs read");
179 dprint("%max_frequency: %lu", max_frequency);
180 dprint("aperf_diff: %llu\n", aperf_diff);
181 dprint("mperf_diff: %llu\n", mperf_diff);
182 dprint("avg freq: %llu\n", *count);
183 return 0;
184 }
185
mperf_start(void)186 static int mperf_start(void)
187 {
188 int cpu;
189 unsigned long long dbg;
190
191 clock_gettime(CLOCK_REALTIME, &time_start);
192 mperf_get_tsc(&tsc_at_measure_start);
193
194 for (cpu = 0; cpu < cpu_count; cpu++)
195 mperf_init_stats(cpu);
196
197 mperf_get_tsc(&dbg);
198 dprint("TSC diff: %llu\n", dbg - tsc_at_measure_start);
199 return 0;
200 }
201
mperf_stop(void)202 static int mperf_stop(void)
203 {
204 unsigned long long dbg;
205 int cpu;
206
207 for (cpu = 0; cpu < cpu_count; cpu++)
208 mperf_measure_stats(cpu);
209
210 mperf_get_tsc(&tsc_at_measure_end);
211 clock_gettime(CLOCK_REALTIME, &time_end);
212
213 mperf_get_tsc(&dbg);
214 dprint("TSC diff: %llu\n", dbg - tsc_at_measure_end);
215
216 return 0;
217 }
218
219 /*
220 * Mperf register is defined to tick at P0 (maximum) frequency
221 *
222 * Instead of reading out P0 which can be tricky to read out from HW,
223 * we use TSC counter if it reliably ticks at P0/mperf frequency.
224 *
225 * Still try to fall back to:
226 * /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
227 * on older Intel HW without invariant TSC feature.
228 * Or on AMD machines where TSC does not tick at P0 (do not exist yet, but
229 * it's still double checked (MSR_AMD_HWCR)).
230 *
231 * On these machines the user would still get useful mperf
232 * stats when acpi-cpufreq driver is loaded.
233 */
init_maxfreq_mode(void)234 static int init_maxfreq_mode(void)
235 {
236 int ret;
237 unsigned long long hwcr;
238 unsigned long min;
239
240 if (!cpupower_cpu_info.caps & CPUPOWER_CAP_INV_TSC)
241 goto use_sysfs;
242
243 if (cpupower_cpu_info.vendor == X86_VENDOR_AMD) {
244 /* MSR_AMD_HWCR tells us whether TSC runs at P0/mperf
245 * freq.
246 * A test whether hwcr is accessable/available would be:
247 * (cpupower_cpu_info.family > 0x10 ||
248 * cpupower_cpu_info.family == 0x10 &&
249 * cpupower_cpu_info.model >= 0x2))
250 * This should be the case for all aperf/mperf
251 * capable AMD machines and is therefore safe to test here.
252 * Compare with Linus kernel git commit: acf01734b1747b1ec4
253 */
254 ret = read_msr(0, MSR_AMD_HWCR, &hwcr);
255 /*
256 * If the MSR read failed, assume a Xen system that did
257 * not explicitly provide access to it and assume TSC works
258 */
259 if (ret != 0) {
260 dprint("TSC read 0x%x failed - assume TSC working\n",
261 MSR_AMD_HWCR);
262 return 0;
263 } else if (1 & (hwcr >> 24)) {
264 max_freq_mode = MAX_FREQ_TSC_REF;
265 return 0;
266 } else { /* Use sysfs max frequency if available */ }
267 } else if (cpupower_cpu_info.vendor == X86_VENDOR_INTEL) {
268 /*
269 * On Intel we assume mperf (in C0) is ticking at same
270 * rate than TSC
271 */
272 max_freq_mode = MAX_FREQ_TSC_REF;
273 return 0;
274 }
275 use_sysfs:
276 if (cpufreq_get_hardware_limits(0, &min, &max_frequency)) {
277 dprint("Cannot retrieve max freq from cpufreq kernel "
278 "subsystem\n");
279 return -1;
280 }
281 max_freq_mode = MAX_FREQ_SYSFS;
282 return 0;
283 }
284
285 /*
286 * This monitor provides:
287 *
288 * 1) Average frequency a CPU resided in
289 * This always works if the CPU has aperf/mperf capabilities
290 *
291 * 2) C0 and Cx (any sleep state) time a CPU resided in
292 * Works if mperf timer stops ticking in sleep states which
293 * seem to be the case on all current HW.
294 * Both is directly retrieved from HW registers and is independent
295 * from kernel statistics.
296 */
297 struct cpuidle_monitor mperf_monitor;
mperf_register(void)298 struct cpuidle_monitor *mperf_register(void)
299 {
300 if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_APERF))
301 return NULL;
302
303 if (init_maxfreq_mode())
304 return NULL;
305
306 /* Free this at program termination */
307 is_valid = calloc(cpu_count, sizeof(int));
308 mperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
309 aperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
310 mperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
311 aperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
312
313 mperf_monitor.name_len = strlen(mperf_monitor.name);
314 return &mperf_monitor;
315 }
316
mperf_unregister(void)317 void mperf_unregister(void)
318 {
319 free(mperf_previous_count);
320 free(aperf_previous_count);
321 free(mperf_current_count);
322 free(aperf_current_count);
323 free(is_valid);
324 }
325
326 struct cpuidle_monitor mperf_monitor = {
327 .name = "Mperf",
328 .hw_states_num = MPERF_CSTATE_COUNT,
329 .hw_states = mperf_cstates,
330 .start = mperf_start,
331 .stop = mperf_stop,
332 .do_register = mperf_register,
333 .unregister = mperf_unregister,
334 .needs_root = 1,
335 .overflow_s = 922000000 /* 922337203 seconds TSC overflow
336 at 20GHz */
337 };
338 #endif /* #if defined(__i386__) || defined(__x86_64__) */
339