busybox/procps/powertop.c

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/* vi: set sw=4 ts=4: */
/*
* A mini 'powertop' utility:
* Analyze power consumption on Intel-based laptops.
* Based on powertop 1.11.
*
* Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
//applet:IF_POWERTOP(APPLET(powertop, BB_DIR_USR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_POWERTOP) += powertop.o
//config:config POWERTOP
//config: bool "powertop"
//config: default y
//config: help
//config: Analyze power consumption on Intel-based laptops
// XXX This should be configurable
#define ENABLE_FEATURE_POWERTOP_PROCIRQ 1
#include "libbb.h"
//#define debug(fmt, ...) fprintf(stderr, fmt, ## __VA_ARGS__)
#define debug(fmt, ...) ((void)0)
#define BLOATY_HPET_IRQ_NUM_DETECTION 0
#define MAX_CSTATE_COUNT 8
#define IRQCOUNT 40
#define DEFAULT_SLEEP 10
#define DEFAULT_SLEEP_STR "10"
/* Frequency of the ACPI timer */
#define FREQ_ACPI 3579.545
#define FREQ_ACPI_1000 3579545
/* Max filename length of entry in /sys/devices subsystem */
#define BIG_SYSNAME_LEN 16
typedef unsigned long long ullong;
struct line {
char *string;
int count;
/*int disk_count;*/
};
#if ENABLE_FEATURE_POWERTOP_PROCIRQ
struct irqdata {
smallint active;
int number;
ullong count;
char irq_desc[32];
};
#endif
struct globals {
struct line *lines; /* the most often used member */
int lines_cnt;
int lines_cumulative_count;
int maxcstate;
unsigned total_cpus;
smallint cant_enable_timer_stats;
#if ENABLE_FEATURE_POWERTOP_PROCIRQ
# if BLOATY_HPET_IRQ_NUM_DETECTION
smallint scanned_timer_list;
int percpu_hpet_start;
int percpu_hpet_end;
# endif
int interrupt_0;
int total_interrupt;
struct irqdata interrupts[IRQCOUNT];
#endif
ullong start_usage[MAX_CSTATE_COUNT];
ullong last_usage[MAX_CSTATE_COUNT];
ullong start_duration[MAX_CSTATE_COUNT];
ullong last_duration[MAX_CSTATE_COUNT];
#if ENABLE_FEATURE_USE_TERMIOS
struct termios init_settings;
#endif
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)
#if ENABLE_FEATURE_USE_TERMIOS
static void reset_term(void)
{
tcsetattr_stdin_TCSANOW(&G.init_settings);
}
static void sig_handler(int signo UNUSED_PARAM)
{
reset_term();
_exit(EXIT_FAILURE);
}
#endif
static int write_str_to_file(const char *fname, const char *str)
{
FILE *fp = fopen_for_write(fname);
if (!fp)
return 1;
fputs(str, fp);
fclose(fp);
return 0;
}
/* Make it more readable */
#define start_timer() write_str_to_file("/proc/timer_stats", "1\n")
#define stop_timer() write_str_to_file("/proc/timer_stats", "0\n")
static NOINLINE void clear_lines(void)
{
int i;
if (G.lines) {
for (i = 0; i < G.lines_cnt; i++)
free(G.lines[i].string);
free(G.lines);
G.lines_cnt = 0;
G.lines = NULL;
}
}
static void update_lines_cumulative_count(void)
{
int i;
for (i = 0; i < G.lines_cnt; i++)
G.lines_cumulative_count += G.lines[i].count;
}
static int line_compare(const void *p1, const void *p2)
{
const struct line *a = p1;
const struct line *b = p2;
return (b->count /*+ 50 * b->disk_count*/) - (a->count /*+ 50 * a->disk_count*/);
}
static void sort_lines(void)
{
qsort(G.lines, G.lines_cnt, sizeof(G.lines[0]), line_compare);
}
/* Save C-state usage and duration. Also update maxcstate. */
static void read_cstate_counts(ullong *usage, ullong *duration)
{
DIR *dir;
struct dirent *d;
dir = opendir("/proc/acpi/processor");
if (!dir)
return;
while ((d = readdir(dir)) != NULL) {
FILE *fp;
char buf[192];
int level;
int len;
len = strlen(d->d_name); /* "CPUnn" */
if (len < 3 || len > BIG_SYSNAME_LEN)
continue;
sprintf(buf, "%s/%s/power", "/proc/acpi/processor", d->d_name);
fp = fopen_for_read(buf);
if (!fp)
continue;
// Example file contents:
// active state: C0
// max_cstate: C8
// maximum allowed latency: 2000000000 usec
// states:
// C1: type[C1] promotion[--] demotion[--] latency[001] usage[00006173] duration[00000000000000000000]
// C2: type[C2] promotion[--] demotion[--] latency[001] usage[00085191] duration[00000000000083024907]
// C3: type[C3] promotion[--] demotion[--] latency[017] usage[01017622] duration[00000000017921327182]
level = 0;
while (fgets(buf, sizeof(buf), fp)) {
char *p = strstr(buf, "age[");
if (!p)
continue;
p += 4;
usage[level] += bb_strtoull(p, NULL, 10) + 1;
p = strstr(buf, "ation[");
if (!p)
continue;
p += 6;
duration[level] += bb_strtoull(p, NULL, 10);
if (level >= MAX_CSTATE_COUNT-1)
break;
level++;
if (level > G.maxcstate) /* update maxcstate */
G.maxcstate = level;
}
fclose(fp);
}
closedir(dir);
}
/* Add line and/or update count */
static void save_line(const char *string, int count)
{
int i;
for (i = 0; i < G.lines_cnt; i++) {
if (strcmp(string, G.lines[i].string) == 0) {
/* It's already there, only update count */
G.lines[i].count += count;
return;
}
}
/* Add new line */
G.lines = xrealloc_vector(G.lines, 4, G.lines_cnt);
G.lines[G.lines_cnt].string = xstrdup(string);
G.lines[G.lines_cnt].count = count;
/*G.lines[G.lines_cnt].disk_count = 0;*/
G.lines_cnt++;
}
#if ENABLE_FEATURE_POWERTOP_PROCIRQ
static int is_hpet_irq(const char *name)
{
char *p;
# if BLOATY_HPET_IRQ_NUM_DETECTION
long hpet_chan;
/* Learn the range of existing hpet timers. This is done once */
if (!G.scanned_timer_list) {
FILE *fp;
char buf[80];
G.scanned_timer_list = true;
fp = fopen_for_read("/proc/timer_list");
if (!fp)
return 0;
while (fgets(buf, sizeof(buf), fp)) {
p = strstr(buf, "Clock Event Device: hpet");
if (!p)
continue;
p += sizeof("Clock Event Device: hpet")-1;
if (!isdigit(*p))
continue;
hpet_chan = xatoi_positive(p);
if (hpet_chan < G.percpu_hpet_start)
G.percpu_hpet_start = hpet_chan;
if (hpet_chan > G.percpu_hpet_end)
G.percpu_hpet_end = hpet_chan;
}
fclose(fp);
}
# endif
//TODO: optimize
p = strstr(name, "hpet");
if (!p)
return 0;
p += 4;
if (!isdigit(*p))
return 0;
# if BLOATY_HPET_IRQ_NUM_DETECTION
hpet_chan = xatoi_positive(p);
if (hpet_chan < G.percpu_hpet_start || hpet_chan > G.percpu_hpet_end)
return 0;
# endif
return 1;
}
/* Save new IRQ count, return delta from old one */
static int save_irq_count(int irq, ullong count)
{
int unused = IRQCOUNT;
int i;
for (i = 0; i < IRQCOUNT; i++) {
if (G.interrupts[i].active && G.interrupts[i].number == irq) {
ullong old = G.interrupts[i].count;
G.interrupts[i].count = count;
return count - old;
}
if (!G.interrupts[i].active && unused > i)
unused = i;
}
if (unused < IRQCOUNT) {
G.interrupts[unused].active = 1;
G.interrupts[unused].count = count;
G.interrupts[unused].number = irq;
}
return count;
}
/* Read /proc/interrupts, save IRQ counts and IRQ description */
static void process_irq_counts(void)
{
FILE *fp;
char buf[128];
/* Reset values */
G.interrupt_0 = 0;
G.total_interrupt = 0;
fp = xfopen_for_read("/proc/interrupts");
while (fgets(buf, sizeof(buf), fp)) {
char irq_desc[sizeof(" <kernel IPI> : ") + sizeof(buf)];
char *p;
const char *name;
int nr;
ullong count;
ullong delta;
p = strchr(buf, ':');
if (!p)
continue;
/* 0: 143646045 153901007 IO-APIC-edge timer
* ^
*/
*p = '\0';
/* Deal with non-maskable interrupts -- make up fake numbers */
nr = index_in_strings("NMI\0RES\0CAL\0TLB\0TRM\0THR\0SPU\0", buf);
if (nr >= 0) {
nr += 20000;
} else {
/* bb_strtou doesn't eat leading spaces, using strtoul */
errno = 0;
nr = strtoul(buf, NULL, 10);
if (errno)
continue;
}
p++;
/* 0: 143646045 153901007 IO-APIC-edge timer
* ^
*/
/* Sum counts for this IRQ */
count = 0;
while (1) {
char *tmp;
p = skip_whitespace(p);
if (!isdigit(*p))
break;
count += bb_strtoull(p, &tmp, 10);
p = tmp;
}
/* 0: 143646045 153901007 IO-APIC-edge timer
* NMI: 1 2 Non-maskable interrupts
* ^
*/
if (nr < 20000) {
/* Skip to the interrupt name, e.g. 'timer' */
p = strchr(p, ' ');
if (!p)
continue;
p = skip_whitespace(p);
}
name = p;
strchrnul(name, '\n')[0] = '\0';
/* Save description of the interrupt */
if (nr >= 20000)
sprintf(irq_desc, " <kernel IPI> : %s", name);
else
sprintf(irq_desc, " <interrupt> : %s", name);
delta = save_irq_count(nr, count);
/* Skip per CPU timer interrupts */
if (is_hpet_irq(name))
continue;
if (nr != 0 && delta != 0)
save_line(irq_desc, delta);
if (nr == 0)
G.interrupt_0 = delta;
else
G.total_interrupt += delta;
}
fclose(fp);
}
#else /* !ENABLE_FEATURE_POWERTOP_PROCIRQ */
# define process_irq_counts() ((void)0)
#endif
static NOINLINE int process_timer_stats(void)
{
char buf[128];
char line[15 + 3 + 128];
int n;
FILE *fp;
buf[0] = '\0';
n = 0;
fp = NULL;
if (!G.cant_enable_timer_stats)
fp = fopen_for_read("/proc/timer_stats");
if (fp) {
// Example file contents:
// Timer Stats Version: v0.2
// Sample period: 1.329 s
// 76, 0 swapper hrtimer_start_range_ns (tick_sched_timer)
// 88, 0 swapper hrtimer_start_range_ns (tick_sched_timer)
// 24, 3787 firefox hrtimer_start_range_ns (hrtimer_wakeup)
// 46D, 1136 kondemand/1 do_dbs_timer (delayed_work_timer_fn)
// ...
// 1, 1656 Xorg hrtimer_start_range_ns (hrtimer_wakeup)
// 1, 2159 udisks-daemon hrtimer_start_range_ns (hrtimer_wakeup)
// 331 total events, 249.059 events/sec
while (fgets(buf, sizeof(buf), fp)) {
const char *count, *process, *func;
char *p;
int idx;
unsigned cnt;
count = skip_whitespace(buf);
p = strchr(count, ',');
if (!p)
continue;
*p++ = '\0';
cnt = bb_strtou(count, NULL, 10);
if (strcmp(skip_non_whitespace(count), " total events") == 0) {
#if ENABLE_FEATURE_POWERTOP_PROCIRQ
n = cnt / G.total_cpus;
if (n > 0 && n < G.interrupt_0) {
sprintf(line, " <interrupt> : %s", "extra timer interrupt");
save_line(line, G.interrupt_0 - n);
}
#endif
break;
}
if (strchr(count, 'D'))
continue; /* deferred */
p = skip_whitespace(p); /* points to pid now */
process = NULL;
get_func_name:
p = strchr(p, ' ');
if (!p)
continue;
*p++ = '\0';
p = skip_whitespace(p);
if (process == NULL) {
process = p;
goto get_func_name;
}
func = p;
//if (strcmp(process, "swapper") == 0
// && strcmp(func, "hrtimer_start_range_ns (tick_sched_timer)\n") == 0
//) {
// process = "[kernel scheduler]";
// func = "Load balancing tick";
//}
if (strncmp(func, "tick_nohz_", 10) == 0)
continue;
if (strncmp(func, "tick_setup_sched_timer", 20) == 0)
continue;
//if (strcmp(process, "powertop") == 0)
// continue;
idx = index_in_strings("insmod\0modprobe\0swapper\0", process);
if (idx != -1) {
process = idx < 2 ? "[kernel module]" : "<kernel core>";
}
strchrnul(p, '\n')[0] = '\0';
// 46D\01136\0kondemand/1\0do_dbs_timer (delayed_work_timer_fn)
// ^ ^ ^
// count process func
//if (strchr(process, '['))
sprintf(line, "%15.15s : %s", process, func);
//else
// sprintf(line, "%s", process);
save_line(line, cnt);
}
fclose(fp);
}
return n;
}
#ifdef __i386__
/*
* Get information about CPU using CPUID opcode.
*/
static void cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
unsigned int *edx)
{
/* EAX value specifies what information to return */
__asm__(
" pushl %%ebx\n" /* Save EBX */
" cpuid\n"
" movl %%ebx, %1\n" /* Save content of EBX */
" popl %%ebx\n" /* Restore EBX */
: "=a"(*eax), /* Output */
"=r"(*ebx),
"=c"(*ecx),
"=d"(*edx)
: "0"(*eax), /* Input */
"1"(*ebx),
"2"(*ecx),
"3"(*edx)
/* No clobbered registers */
);
}
#endif
#ifdef __i386__
static NOINLINE void print_intel_cstates(void)
{
int bios_table[8] = { 0 };
int nbios = 0;
DIR *cpudir;
struct dirent *d;
int i;
unsigned eax, ebx, ecx, edx;
cpudir = opendir("/sys/devices/system/cpu");
if (!cpudir)
return;
/* Loop over cpuN entries */
while ((d = readdir(cpudir)) != NULL) {
DIR *dir;
int len;
char fname[sizeof("/sys/devices/system/cpu//cpuidle//desc") + 2*BIG_SYSNAME_LEN];
len = strlen(d->d_name);
if (len < 3 || len > BIG_SYSNAME_LEN)
continue;
if (!isdigit(d->d_name[3]))
continue;
len = sprintf(fname, "%s/%s/cpuidle", "/sys/devices/system/cpu", d->d_name);
dir = opendir(fname);
if (!dir)
continue;
/*
* Every C-state has its own stateN directory, that
* contains a 'time' and a 'usage' file.
*/
while ((d = readdir(dir)) != NULL) {
FILE *fp;
char buf[64];
int n;
n = strlen(d->d_name);
if (n < 3 || n > BIG_SYSNAME_LEN)
continue;
sprintf(fname + len, "/%s/desc", d->d_name);
fp = fopen_for_read(fname);
if (fp) {
char *p = fgets(buf, sizeof(buf), fp);
fclose(fp);
if (!p)
break;
p = strstr(p, "MWAIT ");
if (p) {
int pos;
p += sizeof("MWAIT ") - 1;
pos = (bb_strtoull(p, NULL, 16) >> 4) + 1;
if (pos >= ARRAY_SIZE(bios_table))
continue;
bios_table[pos]++;
nbios++;
}
}
}
closedir(dir);
}
closedir(cpudir);
if (!nbios)
return;
eax = 5;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
if (!edx || !(ecx & 1))
return;
printf("Your CPU supports the following C-states: ");
i = 0;
while (edx) {
if (edx & 7)
printf("C%u ", i);
edx >>= 4;
i++;
}
bb_putchar('\n');
/* Print BIOS C-States */
printf("Your BIOS reports the following C-states: ");
for (i = 0; i < ARRAY_SIZE(bios_table); i++)
if (bios_table[i])
printf("C%u ", i);
bb_putchar('\n');
}
#else
# define print_intel_cstates() ((void)0)
#endif
static void show_timerstats(void)
{
unsigned lines;
/* Get terminal height */
get_terminal_width_height(STDOUT_FILENO, NULL, &lines);
/* We don't have whole terminal just for timerstats */
lines -= 12;
if (!G.cant_enable_timer_stats) {
int i, n = 0;
char strbuf6[6];
puts("\nTop causes for wakeups:");
for (i = 0; i < G.lines_cnt; i++) {
if ((G.lines[i].count > 0 /*|| G.lines[i].disk_count > 0*/)
&& n++ < lines
) {
/* NB: upstream powertop prints "(wakeups/sec)",
* we print just "(wakeup counts)".
*/
/*char c = ' ';
if (G.lines[i].disk_count)
c = 'D';*/
smart_ulltoa5(G.lines[i].count, strbuf6, " KMGTPEZY")[0] = '\0';
printf(/*" %5.1f%% (%s)%c %s\n"*/
" %5.1f%% (%s) %s\n",
G.lines[i].count * 100.0 / G.lines_cumulative_count,
strbuf6, /*c,*/
G.lines[i].string);
}
}
} else {
bb_putchar('\n');
bb_error_msg("no stats available; run as root or"
" enable the timer_stats module");
}
}
// Example display from powertop version 1.11
// Cn Avg residency P-states (frequencies)
// C0 (cpu running) ( 0.5%) 2.00 Ghz 0.0%
// polling 0.0ms ( 0.0%) 1.67 Ghz 0.0%
// C1 mwait 0.0ms ( 0.0%) 1333 Mhz 0.1%
// C2 mwait 0.1ms ( 0.1%) 1000 Mhz 99.9%
// C3 mwait 12.1ms (99.4%)
//
// Wakeups-from-idle per second : 93.6 interval: 15.0s
// no ACPI power usage estimate available
//
// Top causes for wakeups:
// 32.4% ( 26.7) <interrupt> : extra timer interrupt
// 29.0% ( 23.9) <kernel core> : hrtimer_start_range_ns (tick_sched_timer)
// 9.0% ( 7.5) <kernel core> : hrtimer_start (tick_sched_timer)
// 6.5% ( 5.3) <interrupt> : ata_piix
// 5.0% ( 4.1) inetd : hrtimer_start_range_ns (hrtimer_wakeup)
//usage:#define powertop_trivial_usage
//usage: ""
//usage:#define powertop_full_usage "\n\n"
//usage: "Analyze power consumption on Intel-based laptops"
int powertop_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int powertop_main(int UNUSED_PARAM argc, char UNUSED_PARAM **argv)
{
ullong cur_usage[MAX_CSTATE_COUNT];
ullong cur_duration[MAX_CSTATE_COUNT];
char cstate_lines[MAX_CSTATE_COUNT + 2][64];
#if ENABLE_FEATURE_USE_TERMIOS
struct termios new_settings;
struct pollfd pfd[1];
pfd[0].fd = 0;
pfd[0].events = POLLIN;
#endif
INIT_G();
#if ENABLE_FEATURE_POWERTOP_PROCIRQ && BLOATY_HPET_IRQ_NUM_DETECTION
G.percpu_hpet_start = INT_MAX;
G.percpu_hpet_end = INT_MIN;
#endif
/* Print warning when we don't have superuser privileges */
if (geteuid() != 0)
bb_error_msg("run as root to collect enough information");
/* Get number of CPUs */
G.total_cpus = get_cpu_count();
printf("Collecting data for "DEFAULT_SLEEP_STR" seconds\n");
#if ENABLE_FEATURE_USE_TERMIOS
tcgetattr(0, (void *)&G.init_settings);
memcpy(&new_settings, &G.init_settings, sizeof(new_settings));
/* Turn on unbuffered input, turn off echoing */
new_settings.c_lflag &= ~(ISIG | ICANON | ECHO | ECHONL);
/* So we don't forget to reset term settings */
atexit(reset_term);
bb_signals(BB_FATAL_SIGS, sig_handler);
tcsetattr_stdin_TCSANOW(&new_settings);
#endif
/* Collect initial data */
process_irq_counts();
/* Read initial usage and duration */
read_cstate_counts(G.start_usage, G.start_duration);
/* Copy them to "last" */
memcpy(G.last_usage, G.start_usage, sizeof(G.last_usage));
memcpy(G.last_duration, G.start_duration, sizeof(G.last_duration));
/* Display C-states */
print_intel_cstates();
G.cant_enable_timer_stats |= stop_timer(); /* 1 on error */
/* The main loop */
for (;;) {
//double maxsleep = 0.0;
ullong totalticks, totalevents;
int i;
G.cant_enable_timer_stats |= start_timer(); /* 1 on error */
#if !ENABLE_FEATURE_USE_TERMIOS
sleep(DEFAULT_SLEEP);
#else
if (safe_poll(pfd, 1, DEFAULT_SLEEP * 1000) > 0) {
unsigned char c;
if (safe_read(STDIN_FILENO, &c, 1) != 1)
break; /* EOF/error */
if (c == G.init_settings.c_cc[VINTR])
break; /* ^C */
if ((c | 0x20) == 'q')
break;
}
#endif
G.cant_enable_timer_stats |= stop_timer(); /* 1 on error */
clear_lines();
process_irq_counts();
/* Clear the stats */
memset(cur_duration, 0, sizeof(cur_duration));
memset(cur_usage, 0, sizeof(cur_usage));
/* Read them */
read_cstate_counts(cur_usage, cur_duration);
/* Count totalticks and totalevents */
totalticks = totalevents = 0;
for (i = 0; i < MAX_CSTATE_COUNT; i++) {
if (cur_usage[i] != 0) {
totalticks += cur_duration[i] - G.last_duration[i];
totalevents += cur_usage[i] - G.last_usage[i];
}
}
/* Clear the screen */
printf("\033[H\033[J");
/* Clear C-state lines */
memset(&cstate_lines, 0, sizeof(cstate_lines));
if (totalevents == 0 && G.maxcstate <= 1) {
/* This should not happen */
strcpy(cstate_lines[0], "C-state information is not available\n");
} else {
double percentage;
unsigned newticks;
newticks = G.total_cpus * DEFAULT_SLEEP * FREQ_ACPI_1000 - totalticks;
/* Handle rounding errors: do not display negative values */
if ((int)newticks < 0)
newticks = 0;
sprintf(cstate_lines[0], "Cn\t\t Avg residency\n");
percentage = newticks * 100.0 / (G.total_cpus * DEFAULT_SLEEP * FREQ_ACPI_1000);
sprintf(cstate_lines[1], "C0 (cpu running) (%4.1f%%)\n", percentage);
/* Compute values for individual C-states */
for (i = 0; i < MAX_CSTATE_COUNT; i++) {
if (cur_usage[i] != 0) {
double slept;
slept = (cur_duration[i] - G.last_duration[i])
/ (cur_usage[i] - G.last_usage[i] + 0.1) / FREQ_ACPI;
percentage = (cur_duration[i] - G.last_duration[i]) * 100
/ (G.total_cpus * DEFAULT_SLEEP * FREQ_ACPI_1000);
sprintf(cstate_lines[i + 2], "C%u\t\t%5.1fms (%4.1f%%)\n",
i + 1, slept, percentage);
//if (maxsleep < slept)
// maxsleep = slept;
}
}
}
for (i = 0; i < MAX_CSTATE_COUNT + 2; i++)
if (cstate_lines[i][0])
fputs(cstate_lines[i], stdout);
i = process_timer_stats();
#if ENABLE_FEATURE_POWERTOP_PROCIRQ
if (totalevents == 0) {
/* No C-state info available, use timerstats */
totalevents = i * G.total_cpus + G.total_interrupt;
if (i < 0)
totalevents += G.interrupt_0 - i;
}
#endif
/* Upstream powertop prints wakeups per sec per CPU,
* we print just raw wakeup counts.
*/
//TODO: show real seconds (think about manual refresh)
printf("\nWakeups-from-idle in %u seconds: %llu\n",
DEFAULT_SLEEP,
totalevents
);
update_lines_cumulative_count();
sort_lines();
show_timerstats();
fflush(stdout);
/* Clear the stats */
memset(cur_duration, 0, sizeof(cur_duration));
memset(cur_usage, 0, sizeof(cur_usage));
/* Get new values */
read_cstate_counts(cur_usage, cur_duration);
/* Save them */
memcpy(G.last_usage, cur_usage, sizeof(G.last_usage));
memcpy(G.last_duration, cur_duration, sizeof(G.last_duration));
} /* for (;;) */
bb_putchar('\n');
return EXIT_SUCCESS;
}