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#!/usr/bin/env awk -f
function log10(n) {
return log(n)/log(10.0)
}
function merge_meas(val_est, unc_est, val_meas, unc_meas) {
# add (meas - est) delta to the measurement uncertainty
# note: this works when tracking a constant value,
# the first derivative of a constant 'should' be zero
# unc_meas = sqrt(unc_meas^2.0 + (val_meas - val_est)^2.0)
# Kalman filtering compares variances
unc_est = (0.5*unc_est)^2.0
unc_meas = (0.5*unc_meas)^2.0
G_K = (unc_est)/((unc_est) + (unc_meas))
val_est = val_est + G_K*(val_meas - val_est)
unc_est = (unc_est*unc_meas)/(unc_est + unc_meas)
# convert unc_est back to same units as val_est
unc_est = 2.0*sqrt(unc_est)
return sprintf(OFMT OFS OFMT ORS, val_est, unc_est)
}
function sigfig(val, unc) {
ordmag_val = log10(val)
ordmag_unc = log10(unc)
sigfig_unc = sprintf("%.f", 6)
sigfig_val = sprintf("%.f", (ordmag_val - ordmag_unc + sigfig_unc))
ofmt_val = "%." sigfig_val "g"
ofmt_unc = "%." sigfig_unc "g"
return sprintf(ofmt_val OFS ofmt_unc ORS, val, unc)
}
function ck_boottime() {
"sysctl kern.boottime" | getline t_kboot
close("sysctl kern.boottime")
sub("^.*\{", "", t_kboot)
sub("\}.*$", "", t_kboot)
split(t_kboot, t_kboot_arr, ",")
for (i in t_kboot_arr) {
sub("^.*= ", "", t_kboot_arr[i])
}
t_kboot = sprintf(t_kboot_arr[1] "." t_kboot_arr[2])
return t_kboot
}
function ck_cptime() {
t_sys_meas[1] = systime()
t_sys_meas[2] = 1.0
"sysctl kern.cp_time" | getline cptime_cmd
close("sysctl kern.cp_time")
split(merge_meas(t_sys_meas[1], t_sys_meas[2], systime(), 1.0), t_sys_meas)
sub("^.*=", "", cptime_cmd)
gsub(",", OFS, cptime_cmd)
#split(cptime_cmd, cptime_arr, ",")
return sprintf(OFMT OFS "%s", t_sys_meas[1], cptime_cmd)
}
function ck_uptime(t0_est, t0_unc) {
t_sys_meas[1] = systime()
t_sys_meas[2] = 1.0
"uptime" | getline t_up_cmd
close("uptime")
split(merge_meas(t_sys_meas[1], t_sys_meas[2], systime(), 1.0), t_sys_meas)
# estimate (predict) uptime
t_up_est[1] = t_sys_meas[1] - t0_est
t_up_est[2] = t_sys_meas[2] + t0_unc
# evaluate measured uptime
t_up_meas[1] = 0.0
t_up_meas[2] = systime()
sub("^.*up ", "", t_up_cmd)
sub(", load.*$", "", t_up_cmd)
split(t_up_cmd, t_up_cmd_arr, ",")
for (i in t_up_cmd_arr) {
# TODO: add cases for days, months, years, etc.
if (t_up_cmd_arr[i] ~ /day/) {
split(t_up_cmd_arr[i], days)
t_up_meas[1] += 86400.0*(days[1] + 0.0)
(t_up_meas[2] > 86400.0) ? t_up_meas[2] = 86400.0 : t_up_meas[2] += 0.0
}
if (t_up_cmd_arr[i] ~ /hr/) {
split(t_up_cmd_arr[i], hrs)
t_up_meas[1] += 3600.0*(hrs[1] + 0.0)
(t_up_meas[2] > 3600.0) ? t_up_meas[2] = 3600.0 : t_up_meas[2] += 0.0
}
if (t_up_cmd_arr[i] ~ /min/) {
split(t_up_cmd_arr[i], mins)
t_up_meas[1] += (60.0*(mins[1] + 0.0))
(t_up_meas[2] > 60.0) ? t_up_meas[2] = 60.0 : t_up_meas[2] += 0.0
}
if (t_up_cmd_arr[i] ~ /:/) {
split(t_up_cmd_arr[i], hrs_min, ":")
t_up_meas[1] += 3600.0*(hrs_min[1] + 0.0)
(t_up_meas[2] > 3600.0) ? t_up_meas[2] = 3600.0 : t_up_meas[2] += 0.0
t_up_meas[1] += 60.0*(hrs_min[2] + 0.0)
(t_up_meas[2] > 60.0) ? t_up_meas[2] = 60.0 : t_up_meas[2] += 0.0
}
}
# merge predicted and measured uptimes
split(merge_meas(t_up_est[1], t_up_est[2], t_up_meas[1], t_up_meas[2]), t_up_est)
# evaluate measured boot time, t0
t_boot_meas[1] = t_sys_meas[1] - t_up_meas[1]
t_boot_meas[2] = t_sys_meas[2] + t_up_meas[2]
# merge previous and updated boot time, t0
split(merge_meas(t0_est, t0_unc, t_boot_meas[1], t_boot_meas[2]), t_boot_est)
return sigfig(t_boot_est[1], t_boot_est[2])
}
BEGIN {
OFMT="%.21g"
#print("_systime_", systime())
#print("_boottime_", ck_boottime())
printf("%s" ORS, ck_cptime())
# check ARGV for previous estimate
# if (ARGC > 0) {
# ARGV[1] ? t0_est[1] = ARGV[1] : t0_est[1] = 0.0
# ARGV[2] ? t0_est[2] = ARGV[2] : t0_est[2] = systime()
# }
#print("t0_est = ", t0_est[1])
#print("t_boot_unc = ", t0_est[2])
# wait (sleep) based on uncertainty
# print(60.0/t0_est[2])
# check uptime, update estimate
#print(ck_uptime(t0_est[1], t0_est[2]))
}
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