2 * Copyright (c) 2015 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
16 Copyright (c) 2005 Eliot Dresselhaus
18 Permission is hereby granted, free of charge, to any person obtaining
19 a copy of this software and associated documentation files (the
20 "Software"), to deal in the Software without restriction, including
21 without limitation the rights to use, copy, modify, merge, publish,
22 distribute, sublicense, and/or sell copies of the Software, and to
23 permit persons to whom the Software is furnished to do so, subject to
24 the following conditions:
26 The above copyright notice and this permission notice shall be
27 included in all copies or substantial portions of the Software.
29 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
30 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
31 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
32 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
33 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
34 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
35 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
38 #include <vppinfra/os.h>
39 #include <vppinfra/time.h>
40 #include <vppinfra/format.h>
41 #include <vppinfra/cpu.h>
50 /* Not very accurate way of determining cpu clock frequency
51 for unix. Better to use /proc/cpuinfo on linux. */
53 estimate_clock_frequency (f64 sample_time)
55 f64 time_now, time_start, time_limit, freq;
58 time_start = time_now = unix_time_now ();
59 time_limit = time_now + sample_time;
60 t[0] = clib_cpu_time_now ();
61 while (time_now < time_limit)
62 time_now = unix_time_now ();
63 t[1] = clib_cpu_time_now ();
65 freq = (t[1] - t[0]) / (time_now - time_start);
70 /* Fetch cpu frequency via parseing /proc/cpuinfo.
71 Only works for Linux. */
73 clock_frequency_from_proc_filesystem (void)
75 f64 cpu_freq = 1e9; /* better than 40... */
76 f64 ppc_timebase = 0; /* warnings be gone */
77 unformat_input_t input;
79 /* $$$$ aarch64 kernel doesn't report "cpu MHz" */
80 #if defined(__aarch64__)
87 if (unformat_init_file (&input, "/proc/cpuinfo"))
89 while (unformat_check_input (&input) != UNFORMAT_END_OF_INPUT)
91 if (unformat (&input, "cpu MHz : %f", &cpu_freq))
93 else if (unformat (&input, "timebase : %f", &ppc_timebase))
96 unformat_skip_line (&input);
99 unformat_free (&input);
104 /* Override CPU frequency with time base for PPC. */
105 if (ppc_timebase != 0)
106 cpu_freq = ppc_timebase;
111 /* Fetch cpu frequency via reading /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
112 Only works for Linux. */
114 clock_frequency_from_sys_filesystem (void)
117 unformat_input_t input;
119 /* Time stamp always runs at max frequency. */
122 if (unformat_init_file (
123 &input, "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq"))
125 if (unformat (&input, "%f", &cpu_freq))
126 cpu_freq *= 1e3; /* measured in kHz */
127 unformat_free (&input);
134 os_cpu_clock_frequency (void)
136 #if defined (__aarch64__)
137 /* The system counter increments at a fixed frequency. It is distributed
138 * to each core which has registers for reading the current counter value
139 * as well as the clock frequency. The system counter is not clocked at
140 * the same frequency as the core. */
142 asm volatile ("mrs %0, cntfrq_el0":"=r" (hz));
148 u32 __clib_unused eax = 0, ebx = 0, ecx = 0, edx = 0;
149 clib_get_cpuid (0x00, &eax, &ebx, &ecx, &edx);
154 CPUID Leaf 0x15 - Time Stamp Counter and Nominal Core Crystal Clock Info
155 eax - denominator of the TSC/”core crystal clock” ratio
156 ebx - numerator of the TSC/”core crystal clock” ratio
157 ecx - nominal frequency of the core crystal clock in Hz
161 clib_get_cpuid (0x15, &eax, &ebx, &ecx, &edx);
163 return (u64) ecx *ebx / eax;
165 if (max_leaf >= 0x16)
168 CPUID Leaf 0x16 - Processor Frequency Information Leaf
169 eax - Bits 15 - 00: Processor Base Frequency (in MHz).
172 clib_get_cpuid (0x16, &eax, &ebx, &ecx, &edx);
174 return 1e6 * (eax & 0xffff);
179 /* If we have an invariant TSC, use it to estimate the clock frequency */
180 if (clib_cpu_supports_invariant_tsc ())
181 return estimate_clock_frequency (1e-3);
183 /* Next, try /sys version. */
184 cpu_freq = clock_frequency_from_sys_filesystem ();
188 /* Next try /proc version. */
189 cpu_freq = clock_frequency_from_proc_filesystem ();
193 /* If /proc/cpuinfo fails (e.g. not running on Linux) fall back to
194 gettimeofday based estimated clock frequency. */
195 return estimate_clock_frequency (1e-3);
198 #endif /* CLIB_UNIX */
200 /* Initialize time. */
202 clib_time_init (clib_time_t * c)
204 clib_memset (c, 0, sizeof (c[0]));
205 c->clocks_per_second = os_cpu_clock_frequency ();
207 * Sporadic reports of os_cpu_clock_frequency() returning 0.0
208 * in highly parallel container environments.
209 * To avoid immediate division by zero:
210 * Step 1: try estimate_clock_frequency().
211 * Step 2: give up. Pretend we have a 2gHz clock.
213 if (PREDICT_FALSE (c->clocks_per_second == 0.0))
215 c->clocks_per_second = estimate_clock_frequency (1e-3);
216 if (c->clocks_per_second == 0.0)
218 clib_warning ("os_cpu_clock_frequency() returned 0.0, use 2e9...");
219 c->clocks_per_second = 2e9;
222 c->seconds_per_clock = 1 / c->clocks_per_second;
223 c->log2_clocks_per_second = min_log2_u64 ((u64) c->clocks_per_second);
225 /* Verify frequency every 16 sec */
226 c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second + 4;
228 c->last_verify_reference_time = unix_time_now ();
229 c->init_reference_time = c->last_verify_reference_time;
230 c->last_cpu_time = clib_cpu_time_now ();
231 c->init_cpu_time = c->last_verify_cpu_time = c->last_cpu_time;
232 c->total_cpu_time = 0ULL;
235 * Use exponential smoothing, with a half-life of 1 minute
236 * reported_rate(t) = reported_rate(t-1) * K + rate(t)*(1-K)
237 * where K = e**(-1.0/3.75);
238 * 15 samples in 4 minutes
239 * 7.5 samples in 2 minutes,
240 * 3.75 samples in 1 minute, etc.
242 c->damping_constant = exp (-1.0 / 3.75);
246 clib_time_verify_frequency (clib_time_t * c)
248 f64 now_reference, delta_reference, delta_reference_max;
249 f64 delta_clock_in_seconds;
250 u64 now_clock, delta_clock;
251 f64 new_clocks_per_second, delta;
253 /* Ask the kernel and the CPU what time it is... */
254 now_reference = unix_time_now ();
255 now_clock = clib_cpu_time_now ();
257 /* Compute change in the reference clock */
258 delta_reference = now_reference - c->last_verify_reference_time;
260 /* And change in the CPU clock */
261 delta_clock_in_seconds = (f64) (now_clock - c->last_verify_cpu_time) *
262 c->seconds_per_clock;
265 * Recompute vpp start time reference, and total clocks
266 * using the current clock rate
268 c->init_reference_time += (delta_reference - delta_clock_in_seconds);
269 c->total_cpu_time = (now_reference - c->init_reference_time)
270 * c->clocks_per_second;
272 c->last_cpu_time = now_clock;
274 /* Calculate a new clock rate sample */
275 delta_clock = c->last_cpu_time - c->last_verify_cpu_time;
277 c->last_verify_cpu_time = c->last_cpu_time;
278 c->last_verify_reference_time = now_reference;
281 * Is the reported reference interval non-positive,
282 * or off by a factor of two - or 8 seconds - whichever is larger?
283 * Someone reset the clock behind our back.
285 delta_reference_max = (f64) (2ULL << c->log2_clocks_per_frequency_verify) /
286 (f64) (1ULL << c->log2_clocks_per_second);
287 delta_reference_max = delta_reference_max > 8.0 ? delta_reference_max : 8.0;
289 /* Ignore this sample */
290 if (delta_reference <= 0.0 || delta_reference > delta_reference_max)
294 * Reject large frequency changes, another consequence of
295 * system clock changes particularly with old kernels.
297 new_clocks_per_second = ((f64) delta_clock) / delta_reference;
299 /* Compute abs(rate change) */
300 delta = new_clocks_per_second - c->clocks_per_second;
304 /* If rate change > 1%, reject this sample */
305 if (PREDICT_FALSE ((delta / c->clocks_per_second) > .01))
307 clib_warning ("Rejecting large frequency change of %.2f%%",
308 (delta / c->clocks_per_second) * 100.0);
312 /* Add sample to the exponentially-smoothed rate */
313 c->clocks_per_second = c->clocks_per_second * c->damping_constant +
314 (1.0 - c->damping_constant) * new_clocks_per_second;
315 c->seconds_per_clock = 1.0 / c->clocks_per_second;
318 * Recalculate total_cpu_time based on the kernel timebase, and
319 * the calculated clock rate
322 (now_reference - c->init_reference_time) * c->clocks_per_second;
327 format_clib_time (u8 * s, va_list * args)
329 clib_time_t *c = va_arg (*args, clib_time_t *);
330 int verbose = va_arg (*args, int);
331 f64 now, reftime, delta_reftime_in_seconds, error;
333 /* Compute vpp elapsed time from the CPU clock */
334 reftime = unix_time_now ();
335 now = clib_time_now (c);
337 s = format (s, "Time now %.6f", now);
341 /* And also from the kernel */
342 delta_reftime_in_seconds = reftime - c->init_reference_time;
344 error = now - delta_reftime_in_seconds;
346 s = format (s, ", reftime %.6f, error %.6f, clocks/sec %.6f",
347 delta_reftime_in_seconds, error, c->clocks_per_second);
352 * fd.io coding-style-patch-verification: ON
355 * eval: (c-set-style "gnu")