#include <vppinfra/time.h>
#include <vppinfra/format.h>
#include <vppinfra/cpu.h>
+#include <math.h>
#ifdef CLIB_UNIX
static f64
estimate_clock_frequency (f64 sample_time)
{
- /* Round to nearest 100KHz. */
- const f64 round_to_units = 100e5;
-
f64 time_now, time_start, time_limit, freq;
- u64 ifreq, t[2];
+ u64 t[2];
time_start = time_now = unix_time_now ();
time_limit = time_now + sample_time;
t[1] = clib_cpu_time_now ();
freq = (t[1] - t[0]) / (time_now - time_start);
- ifreq = flt_round_nearest (freq / round_to_units);
- freq = ifreq * round_to_units;
return freq;
}
if (fd < 0)
return cpu_freq;
- unformat_init_unix_file (&input, fd);
+ unformat_init_clib_file (&input, fd);
ppc_timebase = 0;
while (unformat_check_input (&input) != UNFORMAT_END_OF_INPUT)
static f64
clock_frequency_from_sys_filesystem (void)
{
- f64 cpu_freq;
+ f64 cpu_freq = 0.0;
int fd;
unformat_input_t input;
if (fd < 0)
goto done;
- unformat_init_unix_file (&input, fd);
- unformat (&input, "%f", &cpu_freq);
+ unformat_init_clib_file (&input, fd);
+ (void) unformat (&input, "%f", &cpu_freq);
cpu_freq *= 1e3; /* measured in kHz */
unformat_free (&input);
close (fd);
f64
os_cpu_clock_frequency (void)
{
+#if defined (__aarch64__)
+ /* The system counter increments at a fixed frequency. It is distributed
+ * to each core which has registers for reading the current counter value
+ * as well as the clock frequency. The system counter is not clocked at
+ * the same frequency as the core. */
+ u64 hz;
+ asm volatile ("mrs %0, cntfrq_el0":"=r" (hz));
+ return (f64) hz;
+#endif
f64 cpu_freq;
+#ifdef __x86_64__
+ u32 __clib_unused eax = 0, ebx = 0, ecx = 0, edx = 0;
+ clib_get_cpuid (0x00, &eax, &ebx, &ecx, &edx);
+ if (eax >= 0x15)
+ {
+ u32 max_leaf = eax;
+ /*
+ CPUID Leaf 0x15 - Time Stamp Counter and Nominal Core Crystal Clock Info
+ eax - denominator of the TSC/”core crystal clock” ratio
+ ebx - numerator of the TSC/”core crystal clock” ratio
+ ecx - nominal frequency of the core crystal clock in Hz
+ edx - reseved
+ */
+
+ clib_get_cpuid (0x15, &eax, &ebx, &ecx, &edx);
+ if (ebx && ecx)
+ return (u64) ecx *ebx / eax;
+
+ if (max_leaf >= 0x16)
+ {
+ /*
+ CPUID Leaf 0x16 - Processor Frequency Information Leaf
+ eax - Bits 15 - 00: Processor Base Frequency (in MHz).
+ */
+
+ clib_get_cpuid (0x16, &eax, &ebx, &ecx, &edx);
+ if (eax)
+ return 1e6 * (eax & 0xffff);
+ }
+ }
+#endif
+
+ /* If we have an invariant TSC, use it to estimate the clock frequency */
if (clib_cpu_supports_invariant_tsc ())
return estimate_clock_frequency (1e-3);
-#if defined (__aarch64__)
- u64 tsc;
- asm volatile ("mrs %0, CNTFRQ_EL0":"=r" (tsc));
- return (f64) tsc;
-#endif
-
- /* First try /sys version. */
+ /* Next, try /sys version. */
cpu_freq = clock_frequency_from_sys_filesystem ();
if (cpu_freq != 0)
return cpu_freq;
void
clib_time_init (clib_time_t * c)
{
- memset (c, 0, sizeof (c[0]));
+ clib_memset (c, 0, sizeof (c[0]));
c->clocks_per_second = os_cpu_clock_frequency ();
+ /*
+ * Sporadic reports of os_cpu_clock_frequency() returning 0.0
+ * in highly parallel container environments.
+ * To avoid immediate division by zero:
+ * Step 1: try estimate_clock_frequency().
+ * Step 2: give up. Pretend we have a 2gHz clock.
+ */
+ if (PREDICT_FALSE (c->clocks_per_second == 0.0))
+ {
+ c->clocks_per_second = estimate_clock_frequency (1e-3);
+ if (c->clocks_per_second == 0.0)
+ {
+ clib_warning ("os_cpu_clock_frequency() returned 0.0, use 2e9...");
+ c->clocks_per_second = 2e9;
+ }
+ }
c->seconds_per_clock = 1 / c->clocks_per_second;
c->log2_clocks_per_second = min_log2_u64 ((u64) c->clocks_per_second);
- /* Initially verify frequency every sec */
- c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second;
+ /* Verify frequency every 16 sec */
+ c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second + 4;
c->last_verify_reference_time = unix_time_now ();
+ c->init_reference_time = c->last_verify_reference_time;
c->last_cpu_time = clib_cpu_time_now ();
c->init_cpu_time = c->last_verify_cpu_time = c->last_cpu_time;
+ c->total_cpu_time = 0ULL;
+
+ /*
+ * Use exponential smoothing, with a half-life of 1 minute
+ * reported_rate(t) = reported_rate(t-1) * K + rate(t)*(1-K)
+ * where K = e**(-1.0/3.75);
+ * 15 samples in 4 minutes
+ * 7.5 samples in 2 minutes,
+ * 3.75 samples in 1 minute, etc.
+ */
+ c->damping_constant = exp (-1.0 / 3.75);
}
void
clib_time_verify_frequency (clib_time_t * c)
{
- f64 now_reference = unix_time_now ();
- f64 dtr = now_reference - c->last_verify_reference_time;
- f64 dtr_max;
- u64 dtc = c->last_cpu_time - c->last_verify_cpu_time;
- f64 round_units = 100e5;
+ f64 now_reference, delta_reference, delta_reference_max;
+ f64 delta_clock_in_seconds;
+ u64 now_clock, delta_clock;
+ f64 new_clocks_per_second, delta;
+
+ /* Ask the kernel and the CPU what time it is... */
+ now_reference = unix_time_now ();
+ now_clock = clib_cpu_time_now ();
+
+ /* Compute change in the reference clock */
+ delta_reference = now_reference - c->last_verify_reference_time;
+
+ /* And change in the CPU clock */
+ delta_clock_in_seconds = (f64) (now_clock - c->last_verify_cpu_time) *
+ c->seconds_per_clock;
+
+ /*
+ * Recompute vpp start time reference, and total clocks
+ * using the current clock rate
+ */
+ c->init_reference_time += (delta_reference - delta_clock_in_seconds);
+ c->total_cpu_time = (now_reference - c->init_reference_time)
+ * c->clocks_per_second;
+
+ c->last_cpu_time = now_clock;
+
+ /* Calculate a new clock rate sample */
+ delta_clock = c->last_cpu_time - c->last_verify_cpu_time;
c->last_verify_cpu_time = c->last_cpu_time;
c->last_verify_reference_time = now_reference;
* or off by a factor of two - or 8 seconds - whichever is larger?
* Someone reset the clock behind our back.
*/
- dtr_max = (f64) (2ULL << c->log2_clocks_per_frequency_verify) /
+ delta_reference_max = (f64) (2ULL << c->log2_clocks_per_frequency_verify) /
(f64) (1ULL << c->log2_clocks_per_second);
- dtr_max = dtr_max > 8.0 ? dtr_max : 8.0;
+ delta_reference_max = delta_reference_max > 8.0 ? delta_reference_max : 8.0;
+
+ /* Ignore this sample */
+ if (delta_reference <= 0.0 || delta_reference > delta_reference_max)
+ return;
- if (dtr <= 0.0 || dtr > dtr_max)
+ /*
+ * Reject large frequency changes, another consequence of
+ * system clock changes particularly with old kernels.
+ */
+ new_clocks_per_second = ((f64) delta_clock) / delta_reference;
+
+ /* Compute abs(rate change) */
+ delta = new_clocks_per_second - c->clocks_per_second;
+ if (delta < 0.0)
+ delta = -delta;
+
+ /* If rate change > 1%, reject this sample */
+ if (PREDICT_FALSE ((delta / c->clocks_per_second) > .01))
{
- c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second;
+ clib_warning ("Rejecting large frequency change of %.2f%%",
+ (delta / c->clocks_per_second) * 100.0);
return;
}
- c->clocks_per_second =
- flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units;
- c->seconds_per_clock = 1 / c->clocks_per_second;
+ /* Add sample to the exponentially-smoothed rate */
+ c->clocks_per_second = c->clocks_per_second * c->damping_constant +
+ (1.0 - c->damping_constant) * new_clocks_per_second;
+ c->seconds_per_clock = 1.0 / c->clocks_per_second;
+
+ /*
+ * Recalculate total_cpu_time based on the kernel timebase, and
+ * the calculated clock rate
+ */
+ c->total_cpu_time =
+ (now_reference - c->init_reference_time) * c->clocks_per_second;
+}
+
+
+u8 *
+format_clib_time (u8 * s, va_list * args)
+{
+ clib_time_t *c = va_arg (*args, clib_time_t *);
+ int verbose = va_arg (*args, int);
+ f64 now, reftime, delta_reftime_in_seconds, error;
+
+ /* Compute vpp elapsed time from the CPU clock */
+ reftime = unix_time_now ();
+ now = clib_time_now (c);
+
+ s = format (s, "Time now %.6f", now);
+ if (verbose == 0)
+ return s;
+
+ /* And also from the kernel */
+ delta_reftime_in_seconds = reftime - c->init_reference_time;
+
+ error = now - delta_reftime_in_seconds;
- /* Double time between verifies; max at 64 secs ~ 1 minute. */
- if (c->log2_clocks_per_frequency_verify < c->log2_clocks_per_second + 6)
- c->log2_clocks_per_frequency_verify += 1;
+ s = format (s, ", reftime %.6f, error %.6f, clocks/sec %.6f",
+ delta_reftime_in_seconds, error, c->clocks_per_second);
+ return (s);
}
/*
Code Review / vpp.git / blobdiff