pg_test_timing.c File Reference

#include "postgres_fe.h"
#include <limits.h>
#include <math.h>
#include "getopt_long.h"
#include "port/pg_bitutils.h"
#include "portability/instr_time.h"

Include dependency graph for pg_test_timing.c:

Go to the source code of this file.

Macros
#define	NUM_DIRECT   10000

Functions
static void	handle_args (int argc, char *argv[])
static void	test_system_timing (void)
static uint64	test_timing (unsigned int duration, TimingClockSourceType source, bool fast_timing)
static void	output (uint64 loop_count)
int	main (int argc, char *argv[])

Variables
static const char *	progname
static unsigned int	test_duration = 3
static double	max_rprct = 99.99
static long long int	histogram [64]
static long long int	direct_histogram [NUM_DIRECT]
static int64	largest_diff
static long long int	largest_diff_count

Macro Definition Documentation

NUM_DIRECT

#define NUM_DIRECT   10000

Definition at line 25 of file pg_test_timing.c.

Function Documentation

handle_args()

static void handle_args ( int  argc, char *  argv[]  )

static

Definition at line 62 of file pg_test_timing.c.

{
    static struct option long_options[] = {
        {"duration", required_argument, NULL, 'd'},
        {"cutoff", required_argument, NULL, 'c'},
        {NULL, 0, NULL, 0}
    };
 
    int         option;         /* Command line option */
    int         optindex = 0;   /* used by getopt_long */
    unsigned long optval;       /* used for option parsing */
    char       *endptr;
 
    if (argc > 1)
    {
        if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
        {
            printf(_("Usage: %s [-d DURATION] [-c CUTOFF]\n"), progname);
            exit(0);
        }
        if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
        {
            puts("pg_test_timing (PostgreSQL) " PG_VERSION);
            exit(0);
        }
    }
 
    while ((option = getopt_long(argc, argv, "d:c:",
                                 long_options, &optindex)) != -1)
    {
        switch (option)
        {
            case 'd':
                errno = 0;
                optval = strtoul(optarg, &endptr, 10);
 
                if (endptr == optarg || *endptr != '\0' ||
                    errno != 0 || optval != (unsigned int) optval)
                {
                    fprintf(stderr, _("%s: invalid argument for option %s\n"),
                            progname, "--duration");
                    fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
                    exit(1);
                }
 
                test_duration = (unsigned int) optval;
                if (test_duration == 0)
                {
                    fprintf(stderr, _("%s: %s must be in range %u..%u\n"),
                            progname, "--duration", 1, UINT_MAX);
                    exit(1);
                }
                break;
 
            case 'c':
                errno = 0;
                max_rprct = strtod(optarg, &endptr);
 
                if (endptr == optarg || *endptr != '\0' || errno != 0)
                {
                    fprintf(stderr, _("%s: invalid argument for option %s\n"),
                            progname, "--cutoff");
                    fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
                    exit(1);
                }
 
                if (max_rprct < 0 || max_rprct > 100)
                {
                    fprintf(stderr, _("%s: %s must be in range %u..%u\n"),
                            progname, "--cutoff", 0, 100);
                    exit(1);
                }
                break;
 
            default:
                fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
                        progname);
                exit(1);
                break;
        }
    }
 
    if (argc > optind)
    {
        fprintf(stderr,
                _("%s: too many command-line arguments (first is \"%s\")\n"),
                progname, argv[optind]);
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
                progname);
        exit(1);
    }
 
    printf(ngettext("Testing timing overhead for %u second.\n\n",
                    "Testing timing overhead for %u seconds.\n\n",
                    test_duration),
           test_duration);
}

References _, fb(), fprintf, getopt_long(), max_rprct, ngettext, optarg, optind, printf, progname, required_argument, and test_duration.

Referenced by main().

main()

int main	(	int	argc,
		char *	argv[]
	)

Definition at line 42 of file pg_test_timing.c.

{
    set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_test_timing"));
    progname = get_progname(argv[0]);
 
    handle_args(argc, argv);
 
    /* initialize timing infrastructure (required for INSTR_* calls) */
    pg_initialize_timing();
 
    test_system_timing();
 
#if PG_INSTR_TSC_CLOCK
    test_tsc_timing();
#endif
 
    return 0;
}

References fb(), get_progname(), handle_args(), pg_initialize_timing(), PG_TEXTDOMAIN, progname, set_pglocale_pgservice(), and test_system_timing().

output()

static void output ( uint64  loop_count )

static

Definition at line 358 of file pg_test_timing.c.

{
    int         max_bit = lengthof(histogram) - 1;
    const char *header1 = _("<= ns");
    const char *header1b = _("ns");
    const char *header2 = /* xgettext:no-c-format */ _("% of total");
    const char *header3 = /* xgettext:no-c-format */ _("running %");
    const char *header4 = _("count");
    int         len1 = strlen(header1);
    int         len2 = strlen(header2);
    int         len3 = strlen(header3);
    int         len4 = strlen(header4);
    double      rprct;
    bool        stopped = false;
 
    if (loop_count == 0)
    {
        printf(_("WARNING: No timing measurements collected. Report this as a bug to <%s>.\n"), PACKAGE_BUGREPORT);
        return;
    }
 
    /* find highest bit value */
    while (max_bit > 0 && histogram[max_bit] == 0)
        max_bit--;
 
    /* set minimum column widths */
    len1 = Max(19, len1);
    len2 = Max(10, len2);
    len3 = Max(10, len3);
    len4 = Max(10, len4);
 
    printf(_("Histogram of timing durations:\n"));
    printf("%*s   %*s %*s %*s\n",
           len1, header1,
           len2, header2,
           len3, header3,
           len4, header4);
 
    rprct = 0;
    for (int i = 0; i <= max_bit; i++)
    {
        double      prct = (double) histogram[i] * 100 / loop_count;
 
        rprct += prct;
        printf("%*llu   %*.4f %*.4f %*lld\n",
               len1, (1ULL << i) - 1,
               len2, prct,
               len3, rprct,
               len4, histogram[i]);
    }
 
    printf(_("\nObserved timing durations up to %.4f%%:\n"), max_rprct);
    printf("%*s   %*s %*s %*s\n",
           len1, header1b,
           len2, header2,
           len3, header3,
           len4, header4);
 
    rprct = 0;
    for (int i = 0; i < NUM_DIRECT; i++)
    {
        if (direct_histogram[i])
        {
            double      prct = (double) direct_histogram[i] * 100 / loop_count;
            bool        print_it = !stopped;
 
            rprct += prct;
 
            /* if largest diff is < NUM_DIRECT, be sure we print it */
            if (i == largest_diff)
            {
                if (stopped)
                    printf("...\n");
                print_it = true;
            }
 
            if (print_it)
                printf("%*d   %*.4f %*.4f %*lld\n",
                       len1, i,
                       len2, prct,
                       len3, rprct,
                       len4, direct_histogram[i]);
            if (rprct >= max_rprct)
                stopped = true;
        }
    }
 
    /* print largest diff when it's outside the array range */
    if (largest_diff >= NUM_DIRECT)
    {
        double      prct = (double) largest_diff_count * 100 / loop_count;
 
        printf("...\n");
        printf("%*lld   %*.4f %*.4f %*lld\n",
               len1, (long long) largest_diff,
               len2, prct,
               len3, 100.0,
               len4, largest_diff_count);
    }
}

test_system_timing()

static void test_system_timing ( void  )

static

Definition at line 165 of file pg_test_timing.c.

{
    uint64      loop_count;
 
    loop_count = test_timing(test_duration, TIMING_CLOCK_SOURCE_SYSTEM, false);
    output(loop_count);
}

References fb(), output, test_duration, test_timing(), and TIMING_CLOCK_SOURCE_SYSTEM.

Referenced by main().

test_timing()

static uint64 test_timing ( unsigned int  duration, TimingClockSourceType  source, bool  fast_timing  )

static

Definition at line 250 of file pg_test_timing.c.

{
    uint64      loop_count = 0;
    instr_time  start_time,
                end_time,
                prev,
                cur;
    const char *time_source = NULL;
 
    if (!pg_set_timing_clock_source(source))
        return 0;
 
    time_source = PG_INSTR_SYSTEM_CLOCK_NAME;
 
#if PG_INSTR_TSC_CLOCK
    if (pg_current_timing_clock_source() == TIMING_CLOCK_SOURCE_TSC)
        time_source = fast_timing ? PG_INSTR_TSC_CLOCK_NAME_FAST : PG_INSTR_TSC_CLOCK_NAME;
#endif
 
    if (fast_timing)
        printf(_("Fast clock source: %s\n"), time_source);
    else if (source == TIMING_CLOCK_SOURCE_SYSTEM)
        printf(_("System clock source: %s\n"), time_source);
    else
        printf(_("Clock source: %s\n"), time_source);
 
    /*
     * Pre-zero the statistics data structures.  They're already zero by
     * default, but this helps bring them into processor cache and avoid
     * possible timing glitches due to COW behavior.
     */
    memset(direct_histogram, 0, sizeof(direct_histogram));
    memset(histogram, 0, sizeof(histogram));
    largest_diff = 0;
    largest_diff_count = 0;
 
    INSTR_TIME_SET_CURRENT(start_time);
    cur = start_time;
 
    end_time = start_time;
    INSTR_TIME_ADD_NANOSEC(end_time, duration * NS_PER_S);
 
    while (INSTR_TIME_GT(end_time, cur))
    {
        int64       diff;
        int32       bits;
        instr_time  diff_time;
 
        prev = cur;
 
        if (fast_timing)
            INSTR_TIME_SET_CURRENT_FAST(cur);
        else
            INSTR_TIME_SET_CURRENT(cur);
 
        diff_time = cur;
        INSTR_TIME_SUBTRACT(diff_time, prev);
        diff = INSTR_TIME_GET_NANOSEC(diff_time);
 
        /* Did time go backwards? */
        if (unlikely(diff < 0))
        {
            fprintf(stderr, _("Detected clock going backwards in time.\n"));
            fprintf(stderr, _("Time warp: %" PRId64 " ns\n"), diff);
            exit(1);
        }
 
        /* What is the highest bit in the time diff? */
        if (diff > 0)
        {
            bits = pg_leftmost_one_pos64(diff) + 1;
            /* histogram should be defined large enough */
            Assert(bits < lengthof(histogram));
        }
        else
            bits = 0;
 
        /* Update appropriate duration bucket */
        histogram[bits]++;
 
        /* Update direct histogram of time diffs */
        if (diff < NUM_DIRECT)
            direct_histogram[diff]++;
 
        /* Also track the largest observed duration, even if >= NUM_DIRECT */
        if (diff > largest_diff)
        {
            largest_diff = diff;
            largest_diff_count = 1;
        }
        else if (diff == largest_diff)
            largest_diff_count++;
 
        loop_count++;
    }
 
    /* Refresh end time to be the actual time spent (vs the target end time) */
    INSTR_TIME_SET_CURRENT(end_time);
 
    INSTR_TIME_SUBTRACT(end_time, start_time);
 
    printf(_("Average loop time including overhead: %0.2f ns\n"),
           INSTR_TIME_GET_DOUBLE(end_time) * NS_PER_S / loop_count);
 
    return loop_count;
}

References _, Assert, cur, direct_histogram, duration, end_time, fb(), fprintf, histogram, INSTR_TIME_ADD_NANOSEC, INSTR_TIME_GET_DOUBLE, INSTR_TIME_GET_NANOSEC, INSTR_TIME_GT, INSTR_TIME_SET_CURRENT, INSTR_TIME_SET_CURRENT_FAST, INSTR_TIME_SUBTRACT, largest_diff, largest_diff_count, lengthof, NS_PER_S, NUM_DIRECT, pg_current_timing_clock_source(), PG_INSTR_SYSTEM_CLOCK_NAME, pg_leftmost_one_pos64(), pg_set_timing_clock_source(), printf, source, start_time, TIMING_CLOCK_SOURCE_SYSTEM, and unlikely.

Referenced by test_system_timing().

Variable Documentation

direct_histogram

long long int direct_histogram[NUM_DIRECT]

static

Definition at line 26 of file pg_test_timing.c.

Referenced by test_timing().

histogram

long long int histogram[64]

static

Definition at line 22 of file pg_test_timing.c.

Referenced by test_timing().

largest_diff

int64 largest_diff

static

Definition at line 29 of file pg_test_timing.c.

Referenced by test_timing().

largest_diff_count

long long int largest_diff_count

static

Definition at line 30 of file pg_test_timing.c.

Referenced by test_timing().

max_rprct

double max_rprct = 99.99

static

Definition at line 19 of file pg_test_timing.c.

Referenced by handle_args().

progname

const char* progname

static

Definition at line 16 of file pg_test_timing.c.

Referenced by handle_args(), and main().

test_duration

unsigned int test_duration = 3

static

Definition at line 18 of file pg_test_timing.c.

Referenced by handle_args(), and test_system_timing().