/* vi: set sw=4 ts=4: */
/*
 * Per-processor statistics, based on sysstat version 9.1.2 by Sebastien Godard
 *
 * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
//config:config MPSTAT
//config:       bool "mpstat (9.8 kb)"
//config:       default y
//config:       help
//config:       Per-processor statistics

//applet:IF_MPSTAT(APPLET(mpstat, BB_DIR_BIN, BB_SUID_DROP))
/* shouldn't be noexec: "mpstat INTERVAL" runs indefinitely */

//kbuild:lib-$(CONFIG_MPSTAT) += mpstat.o

#include "libbb.h"
#include <sys/utsname.h>  /* struct utsname */

//#define debug(fmt, ...) fprintf(stderr, fmt, ## __VA_ARGS__)
#define debug(fmt, ...) ((void)0)

/* Size of /proc/interrupts line, CPU data excluded */
#define INTERRUPTS_LINE    64
/* Maximum number of interrupts */
#define NR_IRQS            256
#define NR_IRQCPU_PREALLOC 3
#define MAX_IRQNAME_LEN    16
#define MAX_PF_NAME        512
/* sysstat 9.0.6 uses width 8, but newer code which also prints /proc/softirqs
 * data needs more: "interrupts" in /proc/softirqs have longer names,
 * most are up to 8 chars, one (BLOCK_IOPOLL) is even longer.
 * We are printing headers in the " IRQNAME/s" form, experimentally
 * anything smaller than 10 chars looks ugly for /proc/softirqs stats.
 */
#define INTRATE_SCRWIDTH      10
#define INTRATE_SCRWIDTH_STR "10"

/* System files */
#define PROCFS_STAT       "/proc/stat"
#define PROCFS_INTERRUPTS "/proc/interrupts"
#define PROCFS_SOFTIRQS   "/proc/softirqs"
#define PROCFS_UPTIME     "/proc/uptime"


#if 1
typedef unsigned long long data_t;
typedef long long idata_t;
#define FMT_DATA "ll"
#define DATA_MAX ULLONG_MAX
#else
typedef unsigned long data_t;
typedef long idata_t;
#define FMT_DATA "l"
#define DATA_MAX ULONG_MAX
#endif


struct stats_irqcpu {
        unsigned interrupts;
        char irq_name[MAX_IRQNAME_LEN];
};

struct stats_cpu {
        data_t cpu_user;
        data_t cpu_nice;
        data_t cpu_system;
        data_t cpu_idle;
        data_t cpu_iowait;
        data_t cpu_steal;
        data_t cpu_irq;
        data_t cpu_softirq;
        data_t cpu_guest;
};

struct stats_irq {
        data_t irq_nr;
};


/* Globals. Sort by size and access frequency. */
struct globals {
        int interval;
        int count;
        unsigned cpu_nr;                /* Number of CPUs */
        unsigned irqcpu_nr;             /* Number of interrupts per CPU */
        unsigned softirqcpu_nr;         /* Number of soft interrupts per CPU */
        unsigned options;
        unsigned hz;
        unsigned cpu_bitmap_len;
        smallint p_option;
        // 9.0.6 does not do it. Try "mpstat -A 1 2" - headers are repeated!
        //smallint header_done;
        //smallint avg_header_done;
        unsigned char *cpu_bitmap;      /* Bit 0: global, bit 1: 1st proc... */
        data_t global_uptime[3];
        data_t per_cpu_uptime[3];
        struct stats_cpu *st_cpu[3];
        struct stats_irq *st_irq[3];
        struct stats_irqcpu *st_irqcpu[3];
        struct stats_irqcpu *st_softirqcpu[3];
        struct tm timestamp[3];
};
#define G (*ptr_to_globals)
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)

/* The selected interrupts statistics (bits in G.options) */
enum {
        D_CPU      = 1 << 0,
        D_IRQ_SUM  = 1 << 1,
        D_IRQ_CPU  = 1 << 2,
        D_SOFTIRQS = 1 << 3,
};


/* Is option on? */
static ALWAYS_INLINE int display_opt(int opt)
{
        return (opt & G.options);
}

#if DATA_MAX > 0xffffffff
/*
 * Handle overflow conditions properly for counters which can have
 * less bits than data_t, depending on the kernel version.
 */
/* Surprisingly, on 32bit inlining is a size win */
static ALWAYS_INLINE data_t overflow_safe_sub(data_t prev, data_t curr)
{
        data_t v = curr - prev;

        if ((idata_t)v < 0     /* curr < prev - counter overflow? */
         && prev <= 0xffffffff /* kernel uses 32bit value for the counter? */
        ) {
                /* Add 33th bit set to 1 to curr, compensating for the overflow */
                /* double shift defeats "warning: left shift count >= width of type" */
                v += ((data_t)1 << 16) << 16;
        }
        return v;
}
#else
static ALWAYS_INLINE data_t overflow_safe_sub(data_t prev, data_t curr)
{
        return curr - prev;
}
#endif

static double percent_value(data_t prev, data_t curr, data_t itv)
{
        return ((double)overflow_safe_sub(prev, curr)) / itv * 100;
}

static double hz_value(data_t prev, data_t curr, data_t itv)
{
        //bb_error_msg("curr:%lld prev:%lld G.hz:%u", curr, prev, G.hz);
        return ((double)overflow_safe_sub(prev, curr)) / itv * G.hz;
}

static ALWAYS_INLINE data_t jiffies_diff(data_t old, data_t new)
{
        data_t diff = new - old;
        return (diff == 0) ? 1 : diff;
}

static int is_cpu_in_bitmap(unsigned cpu)
{
        return G.cpu_bitmap[cpu >> 3] & (1 << (cpu & 7));
}

static void write_irqcpu_stats(struct stats_irqcpu *per_cpu_stats[],
                int total_irqs,
                data_t itv,
                int prev, int current,
                const char *prev_str, const char *current_str)
{
        int j;
        int offset, cpu;
        struct stats_irqcpu *p0, *q0;

        /* Check if number of IRQs has changed */
        if (G.interval != 0) {
                for (j = 0; j <= total_irqs; j++) {
                        p0 = &per_cpu_stats[current][j];
                        if (p0->irq_name[0] != '\0') {
                                q0 = &per_cpu_stats[prev][j];
                                if (strcmp(p0->irq_name, q0->irq_name) != 0) {
                                        /* Strings are different */
                                        break;
                                }
                        }
                }
        }

        /* Print header */
        printf("\n%-11s  CPU", prev_str);
        {
                /* A bit complex code to "buy back" space if one header is too wide.
                 * Here's how it looks like. BLOCK_IOPOLL eats too much space,
                 * and latter headers use smaller width to compensate:
                 * ...BLOCK/s BLOCK_IOPOLL/s TASKLET/s SCHED/s HRTIMER/s  RCU/s
                 * ...   2.32      0.00      0.01     17.58      0.14    141.96
                 */
                int expected_len = 0;
                int printed_len = 0;
                for (j = 0; j < total_irqs; j++) {
                        p0 = &per_cpu_stats[current][j];
                        if (p0->irq_name[0] != '\0') {
                                int n = (INTRATE_SCRWIDTH-3) - (printed_len - expected_len);
                                printed_len += printf(" %*s/s", n > 0 ? n : 0, skip_whitespace(p0->irq_name));
                                expected_len += INTRATE_SCRWIDTH;
                        }
                }
        }
        bb_putchar('\n');

        for (cpu = 1; cpu <= G.cpu_nr; cpu++) {
                /* Check if we want stats about this CPU */
                if (!is_cpu_in_bitmap(cpu) && G.p_option) {
                        continue;
                }

                printf("%-11s %4u", current_str, cpu - 1);

                for (j = 0; j < total_irqs; j++) {
                        /* IRQ field set only for proc 0 */
                        p0 = &per_cpu_stats[current][j];

                        /*
                         * An empty string for irq name means that
                         * interrupt is no longer used.
                         */
                        if (p0->irq_name[0] != '\0') {
                                offset = j;
                                q0 = &per_cpu_stats[prev][offset];

                                /*
                                 * If we want stats for the time since boot
                                 * we have p0->irq != q0->irq.
                                 */
                                if (strcmp(p0->irq_name, q0->irq_name) != 0
                                 && G.interval != 0
                                ) {
                                        if (j) {
                                                offset = j - 1;
                                                q0 = &per_cpu_stats[prev][offset];
                                        }
                                        if (strcmp(p0->irq_name, q0->irq_name) != 0
                                         && (j + 1 < total_irqs)
                                        ) {
                                                offset = j + 1;
                                                q0 = &per_cpu_stats[prev][offset];
                                        }
                                }

                                if (strcmp(p0->irq_name, q0->irq_name) == 0
                                 || G.interval == 0
                                ) {
                                        struct stats_irqcpu *p, *q;
                                        p = &per_cpu_stats[current][(cpu - 1) * total_irqs + j];
                                        q = &per_cpu_stats[prev][(cpu - 1) * total_irqs + offset];
                                        printf("%"INTRATE_SCRWIDTH_STR".2f",
                                                (double)(p->interrupts - q->interrupts) / itv * G.hz);
                                } else {
                                        printf("        N/A");
                                }
                        }
                }
                bb_putchar('\n');
        }
}

static data_t get_per_cpu_interval(const struct stats_cpu *scc,
                const struct stats_cpu *scp)
{
        return ((scc->cpu_user + scc->cpu_nice +
                 scc->cpu_system + scc->cpu_iowait +
                 scc->cpu_idle + scc->cpu_steal +
                 scc->cpu_irq + scc->cpu_softirq) -
                (scp->cpu_user + scp->cpu_nice +
                 scp->cpu_system + scp->cpu_iowait +
                 scp->cpu_idle + scp->cpu_steal +
                 scp->cpu_irq + scp->cpu_softirq));
}

static void print_stats_cpu_struct(const struct stats_cpu *p,
                const struct stats_cpu *c,
                data_t itv)
{
        printf(" %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f\n",
                percent_value(p->cpu_user - p->cpu_guest,
                /**/                          c->cpu_user - c->cpu_guest, itv),
                percent_value(p->cpu_nice   , c->cpu_nice   , itv),
                percent_value(p->cpu_system , c->cpu_system , itv),
                percent_value(p->cpu_iowait , c->cpu_iowait , itv),
                percent_value(p->cpu_irq    , c->cpu_irq    , itv),
                percent_value(p->cpu_softirq, c->cpu_softirq, itv),
                percent_value(p->cpu_steal  , c->cpu_steal  , itv),
                percent_value(p->cpu_guest  , c->cpu_guest  , itv),
                percent_value(p->cpu_idle   , c->cpu_idle   , itv)
        );
}

static void write_stats_core(int prev, int current,
                const char *prev_str, const char *current_str)
{
        struct stats_cpu *scc, *scp;
        data_t itv, global_itv;
        int cpu;

        /* Compute time interval */
        itv = global_itv = jiffies_diff(G.global_uptime[prev], G.global_uptime[current]);

        /* Reduce interval to one CPU */
        if (G.cpu_nr > 1)
                itv = jiffies_diff(G.per_cpu_uptime[prev], G.per_cpu_uptime[current]);

        /* Print CPU stats */
        if (display_opt(D_CPU)) {

                ///* This is done exactly once */
                //if (!G.header_done) {
                        printf("\n%-11s  CPU    %%usr   %%nice    %%sys %%iowait    %%irq   %%soft  %%steal  %%guest   %%idle\n",
                                prev_str
                        );
                //      G.header_done = 1;
                //}

                for (cpu = 0; cpu <= G.cpu_nr; cpu++) {
                        data_t per_cpu_itv;

                        /* Print stats about this particular CPU? */
                        if (!is_cpu_in_bitmap(cpu))
                                continue;

                        scc = &G.st_cpu[current][cpu];
                        scp = &G.st_cpu[prev][cpu];
                        per_cpu_itv = global_itv;

                        printf((cpu ? "%-11s %4u" : "%-11s  all"), current_str, cpu - 1);
                        if (cpu) {
                                double idle;
                                /*
                                 * If the CPU is offline, then it isn't in /proc/stat,
                                 * so all values are 0.
                                 * NB: Guest time is already included in user time.
                                 */
                                if ((scc->cpu_user | scc->cpu_nice | scc->cpu_system |
                                     scc->cpu_iowait | scc->cpu_idle | scc->cpu_steal |
                                     scc->cpu_irq | scc->cpu_softirq) == 0
                                ) {
                                        /*
                                         * Set current struct fields to values from prev.
                                         * iteration. Then their values won't jump from
                                         * zero, when the CPU comes back online.
                                         */
                                        *scc = *scp;
                                        idle = 0.0;
                                        goto print_zeros;
                                }
                                /* Compute interval again for current proc */
                                per_cpu_itv = get_per_cpu_interval(scc, scp);
                                if (per_cpu_itv == 0) {
                                        /*
                                         * If the CPU is tickless then there is no change in CPU values
                                         * but the sum of values is not zero.
                                         */
                                        idle = 100.0;
 print_zeros:
                                        printf(" %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f %7.2f\n",
                                                0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, idle);
                                        continue;
                                }
                        }
                        print_stats_cpu_struct(scp, scc, per_cpu_itv);
                }
        }

        /* Print total number of IRQs per CPU */
        if (display_opt(D_IRQ_SUM)) {

                ///* Print average header, this is done exactly once */
                //if (!G.avg_header_done) {
                        printf("\n%-11s  CPU    intr/s\n", prev_str);
                //      G.avg_header_done = 1;
                //}

                for (cpu = 0; cpu <= G.cpu_nr; cpu++) {
                        data_t per_cpu_itv;

                        /* Print stats about this CPU? */
                        if (!is_cpu_in_bitmap(cpu))
                                continue;

                        per_cpu_itv = itv;
                        printf((cpu ? "%-11s %4u" : "%-11s  all"), current_str, cpu - 1);
                        if (cpu) {
                                scc = &G.st_cpu[current][cpu];
                                scp = &G.st_cpu[prev][cpu];
                                /* Compute interval again for current proc */
                                per_cpu_itv = get_per_cpu_interval(scc, scp);
                                if (per_cpu_itv == 0) {
                                        printf(" %9.2f\n", 0.0);
                                        continue;
                                }
                        }
                        //bb_error_msg("G.st_irq[%u][%u].irq_nr:%lld - G.st_irq[%u][%u].irq_nr:%lld",
                        // current, cpu, G.st_irq[prev][cpu].irq_nr, prev, cpu, G.st_irq[current][cpu].irq_nr);
                        printf(" %9.2f\n", hz_value(G.st_irq[prev][cpu].irq_nr, G.st_irq[current][cpu].irq_nr, per_cpu_itv));
                }
        }

        if (display_opt(D_IRQ_CPU)) {
                write_irqcpu_stats(G.st_irqcpu, G.irqcpu_nr,
                                itv,
                                prev, current,
                                prev_str, current_str
                );
        }

        if (display_opt(D_SOFTIRQS)) {
                write_irqcpu_stats(G.st_softirqcpu, G.softirqcpu_nr,
                                itv,
                                prev, current,
                                prev_str, current_str
                );
        }
}

/*
 * Print the statistics
 */
static void write_stats(int current)
{
        char prev_time[16];
        char curr_time[16];

        strftime(prev_time, sizeof(prev_time), "%X", &G.timestamp[!current]);
        strftime(curr_time, sizeof(curr_time), "%X", &G.timestamp[current]);

        write_stats_core(!current, current, prev_time, curr_time);
}

static void write_stats_avg(int current)
{
        write_stats_core(2, current, "Average:", "Average:");
}

/*
 * Read CPU statistics
 */
static void get_cpu_statistics(struct stats_cpu *cpu, data_t *up, data_t *up0)
{
        FILE *fp;
        char buf[1024];

        fp = xfopen_for_read(PROCFS_STAT);

        while (fgets(buf, sizeof(buf), fp)) {
                data_t sum;
                unsigned cpu_number;
                struct stats_cpu *cp;

                if (!starts_with_cpu(buf))
                        continue; /* not "cpu" */

                cp = cpu; /* for "cpu " case */
                if (buf[3] != ' ') {
                        /* "cpuN " */
                        if (G.cpu_nr == 0
                         || sscanf(buf + 3, "%u ", &cpu_number) != 1
                         || cpu_number >= G.cpu_nr
                        ) {
                                continue;
                        }
                        cp = &cpu[cpu_number + 1];
                }

                /* Read the counters, save them */
                /* Not all fields have to be present */
                memset(cp, 0, sizeof(*cp));
                sscanf(buf, "%*s"
                        " %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u"
                        " %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u"
                        " %"FMT_DATA"u %"FMT_DATA"u %"FMT_DATA"u",
                        &cp->cpu_user, &cp->cpu_nice, &cp->cpu_system,
                        &cp->cpu_idle, &cp->cpu_iowait, &cp->cpu_irq,
                        &cp->cpu_softirq, &cp->cpu_steal, &cp->cpu_guest
                );
                /*
                 * Compute uptime in jiffies (1/HZ), it'll be the sum of
                 * individual CPU's uptimes.
                 * NB: We have to omit cpu_guest, because cpu_user includes it.
                 */
                sum = cp->cpu_user + cp->cpu_nice + cp->cpu_system +
                        cp->cpu_idle + cp->cpu_iowait + cp->cpu_irq +
                        cp->cpu_softirq + cp->cpu_steal;

                if (buf[3] == ' ') {
                        /* "cpu " */
                        *up = sum;
                } else {
                        /* "cpuN " */
                        if (cpu_number == 0 && *up0 != 0) {
                                /* Compute uptime of single CPU */
                                *up0 = sum;
                        }
                }
        }
        fclose(fp);
}

/*
 * Read IRQs from /proc/stat
 */
static void get_irqs_from_stat(struct stats_irq *irq)
{
        FILE *fp;
        char buf[1024];

        fp = xfopen_for_read(PROCFS_STAT);

        while (fgets(buf, sizeof(buf), fp)) {
                //bb_error_msg("/proc/stat:'%s'", buf);
                if (is_prefixed_with(buf, "intr ")) {
                        /* Read total number of IRQs since system boot */
                        sscanf(buf + 5, "%"FMT_DATA"u", &irq->irq_nr);
                }
        }

        fclose(fp);
}

/*
 * Read stats from /proc/interrupts or /proc/softirqs
 */
static void get_irqs_from_interrupts(const char *fname,
                struct stats_irqcpu *per_cpu_stats[],
                int irqs_per_cpu, int current)
{
        FILE *fp;
        struct stats_irq *irq_i;
        struct stats_irqcpu *ic;
        char *buf;
        unsigned buflen;
        unsigned cpu;
        unsigned irq;
        int cpu_index[G.cpu_nr];
        int iindex;

// Moved to caller.
// Otherwise reading of /proc/softirqs
// was resetting counts to 0 after we painstakingly collected them from
// /proc/interrupts. Which resulted in:
// 01:32:47 PM  CPU    intr/s
// 01:32:47 PM  all    591.47
// 01:32:47 PM    0      0.00 <= ???
// 01:32:47 PM    1      0.00 <= ???
//      for (cpu = 1; cpu <= G.cpu_nr; cpu++) {
//              G.st_irq[current][cpu].irq_nr = 0;
//              //bb_error_msg("G.st_irq[%u][%u].irq_nr=0", current, cpu);
//      }

        fp = fopen_for_read(fname);
        if (!fp)
                return;

        buflen = INTERRUPTS_LINE + 16 * G.cpu_nr;
        buf = xmalloc(buflen);

        /* Parse header and determine, which CPUs are online */
        iindex = 0;
        while (fgets(buf, buflen, fp)) {
                char *cp, *next;
                next = buf;
                while ((cp = strstr(next, "CPU")) != NULL
                 && iindex < G.cpu_nr
                ) {
                        cpu = strtoul(cp + 3, &next, 10);
                        cpu_index[iindex++] = cpu;
                }
                if (iindex) /* We found header */
                        break;
        }

        irq = 0;
        while (fgets(buf, buflen, fp)
         && irq < irqs_per_cpu
        ) {
                int len;
                char last_char;
                char *cp;

                /* Skip over "IRQNAME:" */
                cp = strchr(buf, ':');
                if (!cp)
                        continue;
                last_char = cp[-1];

                ic = &per_cpu_stats[current][irq];
                len = cp - buf;
                if (len >= sizeof(ic->irq_name)) {
                        len = sizeof(ic->irq_name) - 1;
                }
                safe_strncpy(ic->irq_name, buf, len + 1);
                //bb_error_msg("%s: irq%d:'%s' buf:'%s'", fname, irq, ic->irq_name, buf);
                cp++;

                for (cpu = 0; cpu < iindex; cpu++) {
                        char *next;
                        ic = &per_cpu_stats[current][cpu_index[cpu] * irqs_per_cpu + irq];
                        irq_i = &G.st_irq[current][cpu_index[cpu] + 1];
                        ic->interrupts = strtoul(cp, &next, 10);
                        /* Count only numerical IRQs */
                        if (isdigit(last_char)) {
                                irq_i->irq_nr += ic->interrupts;
                                //bb_error_msg("G.st_irq[%u][%u].irq_nr + %u = %lld",
                                // current, cpu_index[cpu] + 1, ic->interrupts, irq_i->irq_nr);
                        }
                        cp = next;
                }
                irq++;
        }
        fclose(fp);
        free(buf);

        while (irq < irqs_per_cpu) {
                /* Number of interrupts per CPU has changed */
                ic = &per_cpu_stats[current][irq];
                ic->irq_name[0] = '\0'; /* False interrupt */
                irq++;
        }
}

static void get_uptime(data_t *uptime)
{
        FILE *fp;
        char buf[sizeof(long)*3 * 2 + 4]; /* enough for long.long */
        unsigned long uptime_sec, decimal;

        fp = xfopen_for_read(PROCFS_UPTIME);
        if (fgets(buf, sizeof(buf), fp)) {
                if (sscanf(buf, "%lu.%lu", &uptime_sec, &decimal) == 2) {
                        *uptime = (data_t)uptime_sec * G.hz + decimal * G.hz / 100;
                }
        }

        fclose(fp);
}

static void get_localtime(struct tm *tm)
{
        time_t timer;
        time(&timer);
        localtime_r(&timer, tm);
}

static void alarm_handler(int sig UNUSED_PARAM)
{
        signal(SIGALRM, alarm_handler);
        alarm(G.interval);
}

static void main_loop(void)
{
        unsigned current;
        unsigned cpus;

        /* Read the stats */
        if (G.cpu_nr > 1) {
                G.per_cpu_uptime[0] = 0;
                get_uptime(&G.per_cpu_uptime[0]);
        }

        get_cpu_statistics(G.st_cpu[0], &G.global_uptime[0], &G.per_cpu_uptime[0]);

        if (display_opt(D_IRQ_SUM))
                get_irqs_from_stat(G.st_irq[0]);

        if (display_opt(D_IRQ_SUM | D_IRQ_CPU))
                get_irqs_from_interrupts(PROCFS_INTERRUPTS, G.st_irqcpu,
                                        G.irqcpu_nr, 0);

        if (display_opt(D_SOFTIRQS))
                get_irqs_from_interrupts(PROCFS_SOFTIRQS, G.st_softirqcpu,
                                        G.softirqcpu_nr, 0);

        if (G.interval == 0) {
                /* Display since boot time */
                cpus = G.cpu_nr + 1;
                G.timestamp[1] = G.timestamp[0];
                memset(G.st_cpu[1], 0, sizeof(G.st_cpu[1][0]) * cpus);
                memset(G.st_irq[1], 0, sizeof(G.st_irq[1][0]) * cpus);
                memset(G.st_irqcpu[1], 0, sizeof(G.st_irqcpu[1][0]) * cpus * G.irqcpu_nr);
                memset(G.st_softirqcpu[1], 0, sizeof(G.st_softirqcpu[1][0]) * cpus * G.softirqcpu_nr);

                write_stats(0);

                /* And we're done */
                return;
        }

        /* Set a handler for SIGALRM */
        alarm_handler(0);

        /* Save the stats we already have. We need them to compute the average */
        G.timestamp[2] = G.timestamp[0];
        G.global_uptime[2] = G.global_uptime[0];
        G.per_cpu_uptime[2] = G.per_cpu_uptime[0];
        cpus = G.cpu_nr + 1;
        memcpy(G.st_cpu[2], G.st_cpu[0], sizeof(G.st_cpu[0][0]) * cpus);
        memcpy(G.st_irq[2], G.st_irq[0], sizeof(G.st_irq[0][0]) * cpus);
        memcpy(G.st_irqcpu[2], G.st_irqcpu[0], sizeof(G.st_irqcpu[0][0]) * cpus * G.irqcpu_nr);
        if (display_opt(D_SOFTIRQS)) {
                memcpy(G.st_softirqcpu[2], G.st_softirqcpu[0],
                        sizeof(G.st_softirqcpu[0][0]) * cpus * G.softirqcpu_nr);
        }

        current = 1;
        while (1) {
                /* Suspend until a signal is received */
                pause();

                /* Set structures to 0 to distinguish off/online CPUs */
                memset(&G.st_cpu[current][/*cpu:*/ 1], 0, sizeof(G.st_cpu[0][0]) * G.cpu_nr);

                get_localtime(&G.timestamp[current]);

                /* Read stats */
                if (G.cpu_nr > 1) {
                        G.per_cpu_uptime[current] = 0;
                        get_uptime(&G.per_cpu_uptime[current]);
                }
                get_cpu_statistics(G.st_cpu[current], &G.global_uptime[current], &G.per_cpu_uptime[current]);

                if (display_opt(D_IRQ_SUM))
                        get_irqs_from_stat(G.st_irq[current]);

                if (display_opt(D_IRQ_SUM | D_IRQ_CPU)) {
                        int cpu;
                        for (cpu = 1; cpu <= G.cpu_nr; cpu++) {
                                G.st_irq[current][cpu].irq_nr = 0;
                        }
                        /* accumulates .irq_nr */
                        get_irqs_from_interrupts(PROCFS_INTERRUPTS, G.st_irqcpu,
                                        G.irqcpu_nr, current);
                }

                if (display_opt(D_SOFTIRQS))
                        get_irqs_from_interrupts(PROCFS_SOFTIRQS,
                                        G.st_softirqcpu,
                                        G.softirqcpu_nr, current);

                write_stats(current);

                if (G.count > 0) {
                        if (--G.count == 0)
                                break;
                }

                current ^= 1;
        }

        /* Print average statistics */
        write_stats_avg(current);
}

/* Initialization */

static void alloc_struct(int cpus)
{
        int i;
        for (i = 0; i < 3; i++) {
                G.st_cpu[i] = xzalloc(sizeof(G.st_cpu[i][0]) * cpus);
                G.st_irq[i] = xzalloc(sizeof(G.st_irq[i][0]) * cpus);
                G.st_irqcpu[i] = xzalloc(sizeof(G.st_irqcpu[i][0]) * cpus * G.irqcpu_nr);
                G.st_softirqcpu[i] = xzalloc(sizeof(G.st_softirqcpu[i][0]) * cpus * G.softirqcpu_nr);
        }
        G.cpu_bitmap_len = (cpus >> 3) + 1;
        G.cpu_bitmap = xzalloc(G.cpu_bitmap_len);
}

static void print_header(struct tm *t)
{
        char cur_date[16];
        struct utsname uts;

        /* Get system name, release number and hostname */
        uname(&uts);

        strftime(cur_date, sizeof(cur_date), "%x", t);

        printf("%s %s (%s)\t%s\t_%s_\t(%u CPU)\n",
                uts.sysname, uts.release, uts.nodename, cur_date, uts.machine, G.cpu_nr);
}

/*
 * Get number of interrupts available per processor
 */
static int get_irqcpu_nr(const char *f, int max_irqs)
{
        FILE *fp;
        char *line;
        unsigned linelen;
        unsigned irq;

        fp = fopen_for_read(f);
        if (!fp)  /* No interrupts file */
                return 0;

        linelen = INTERRUPTS_LINE + 16 * G.cpu_nr;
        line = xmalloc(linelen);

        irq = 0;
        while (fgets(line, linelen, fp)
         && irq < max_irqs
        ) {
                int p = strcspn(line, ":");
                if ((p > 0) && (p < 16))
                        irq++;
        }

        fclose(fp);
        free(line);

        return irq;
}

//usage:#define mpstat_trivial_usage
//usage:       "[-A] [-I SUM|CPU|ALL|SCPU] [-u] [-P num|ALL] [INTERVAL [COUNT]]"
//usage:#define mpstat_full_usage "\n\n"
//usage:       "Per-processor statistics\n"
//usage:     "\n        -A                      Same as -I ALL -u -P ALL"
//usage:     "\n        -I SUM|CPU|ALL|SCPU     Report interrupt statistics"
//usage:     "\n        -P num|ALL              Processor to monitor"
//usage:     "\n        -u                      Report CPU utilization"

int mpstat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mpstat_main(int argc UNUSED_PARAM, char **argv)
{
        char *opt_irq_fmt;
        char *opt_set_cpu;
        int i, opt;
        enum {
                OPT_ALL    = 1 << 0, /* -A */
                OPT_INTS   = 1 << 1, /* -I */
                OPT_SETCPU = 1 << 2, /* -P */
                OPT_UTIL   = 1 << 3, /* -u */
        };

        /* Dont buffer data if redirected to a pipe */
        setbuf(stdout, NULL);

        INIT_G();

        G.interval = -1;

        /* Get number of processors */
        G.cpu_nr = get_cpu_count();

        /* Get number of clock ticks per sec */
        G.hz = bb_clk_tck();

        /* Calculate number of interrupts per processor */
        G.irqcpu_nr = get_irqcpu_nr(PROCFS_INTERRUPTS, NR_IRQS) + NR_IRQCPU_PREALLOC;

        /* Calculate number of soft interrupts per processor */
        G.softirqcpu_nr = get_irqcpu_nr(PROCFS_SOFTIRQS, NR_IRQS) + NR_IRQCPU_PREALLOC;

        /* Allocate space for structures. + 1 for global structure. */
        alloc_struct(G.cpu_nr + 1);

        /* Parse and process arguments */
        opt = getopt32(argv, "AI:P:u", &opt_irq_fmt, &opt_set_cpu);
        argv += optind;

        if (*argv) {
                /* Get interval */
                G.interval = xatoi_positive(*argv);
                G.count = -1;
                argv++;
                if (*argv) {
                        /* Get count value */
                        if (G.interval == 0)
                                bb_show_usage();
                        G.count = xatoi_positive(*argv);
                        //if (*++argv)
                        //      bb_show_usage();
                }
        }
        if (G.interval < 0)
                G.interval = 0;

        if (opt & OPT_ALL) {
                G.p_option = 1;
                G.options |= D_CPU + D_IRQ_SUM + D_IRQ_CPU + D_SOFTIRQS;
                /* Select every CPU */
                memset(G.cpu_bitmap, 0xff, G.cpu_bitmap_len);
        }

        if (opt & OPT_INTS) {
                static const char v[] = {
                        D_IRQ_CPU, D_IRQ_SUM, D_SOFTIRQS,
                        D_IRQ_SUM + D_IRQ_CPU + D_SOFTIRQS
                };
                i = index_in_strings("CPU\0SUM\0SCPU\0ALL\0", opt_irq_fmt);
                if (i == -1)
                        bb_show_usage();
                G.options |= v[i];
        }

        if ((opt & OPT_UTIL) /* -u? */
         || G.options == 0  /* nothing? (use default then) */
        ) {
                G.options |= D_CPU;
        }

        if (opt & OPT_SETCPU) {
                char *t;
                G.p_option = 1;

                for (t = strtok(opt_set_cpu, ","); t; t = strtok(NULL, ",")) {
                        if (strcmp(t, "ALL") == 0) {
                                /* Select every CPU */
                                memset(G.cpu_bitmap, 0xff, G.cpu_bitmap_len);
                        } else {
                                /* Get CPU number */
                                unsigned n = xatoi_positive(t);
                                if (n >= G.cpu_nr)
                                        bb_error_msg_and_die("not that many processors");
                                n++;
                                G.cpu_bitmap[n >> 3] |= 1 << (n & 7);
                        }
                }
        }

        if (!G.p_option)
                /* Display global stats */
                G.cpu_bitmap[0] = 1;

        /* Get time */
        get_localtime(&G.timestamp[0]);

        /* Display header */
        print_header(&G.timestamp[0]);

        /* The main loop */
        main_loop();

        if (ENABLE_FEATURE_CLEAN_UP) {
                /* Clean up */
                for (i = 0; i < 3; i++) {
                        free(G.st_cpu[i]);
                        free(G.st_irq[i]);
                        free(G.st_irqcpu[i]);
                        free(G.st_softirqcpu[i]);
                }
                free(G.cpu_bitmap);
                free(&G);
        }

        return EXIT_SUCCESS;
}