count_timer_syscalls.ksh
Posted by Anonymous on Sat 17th Sep 2022 15:52
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modification of post by Anonymous (view diff)

#!/usr/bin/ksh93

#
# count_timer_syscalls.ksh- Count timer syscalls
#
# Tests whether clock_gettime() is implemented via traditional
# syscalls or uses a shortcut (e.g. via shared memory/Linux VDSO)
#
# Written by Roland Mainz <roland.mainz@nrubsig.org>
#

builtin cat
builtin wc
#builtin rm

set -o nounset

function enumerate_clock_sources
{
        typeset s
        typeset dummy aname avalue
        nameref ar="$1"

        s="$( clang -E -dM -m32 -include time.h - < '/dev/null' | \
                egrep \
                        '#[[:space:]]*define[[:space:]]+CLOCK_.+[[:space:]]+[[:digit:]]+'
                )"

        while read dummy aname avalue ; do
                if [[ \
                        "${aname}" != ~(El)CLOCK_ || \
                        "${avalue}" != ~(Elr)[[:digit:]]+ ]] ; then
                        continue
                fi
                integer ar["$aname"].value
                ar["$aname"].name="${aname}"
                ar["$aname"].value="${avalue}"
        done <<<"$s"

        return 0
}

function generate_test_code
{
        nameref ar="$1"
        integer num_testruns=$2

        set -o errexit
        set -o nounset

        printf $"## Generating test code...\n"

        rm -f \
                'generated_count_timer_syscalls.c' \
                'generated_count_timer_syscalls'

        {
                cat <<EOF

/*
 * count_timer_syscalls.c - runs timer NUM_TESTRUNS times,
 * strace can then be used to count syscalls
 *
 * Compile with:
 * $ clang -g -Wall -Wextra count_timer_syscalls.c
 *
 * Written by Roland Mainz <roland.mainz@nrubsig.org>
 *
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <time.h>
#include <sched.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>


#ifndef CLOCK_INVALID
#define CLOCK_INVALID -1
#endif

#define NSEC_PER_SEC (1000000000LL)

#define NUM_TESTRUNS (${num_testruns}UL)


static
clockid_t get_clockid(int fd)
{
        const int CLOCKFD = 3;

        return (((unsigned int) ~fd) << 3) | CLOCKFD;
}


static
void test_loop_on_clock(clockid_t clkid, unsigned long num_cycles)
{
        struct timespec ts;
        unsigned long cycles;

        for(cycles = 0UL ; cycles < num_cycles ; cycles++)
        {
                (void)clock_gettime(clkid, &ts);
                (void)ts;
        }
}


int main(int ac, char *av[])
{
        const char *clockname = av[1];

        (void)puts("# start.");

        if ((ac != 2) || (!clockname)) {
                (void)fprintf(stderr, "%s: Missing clockname argument\n", av[0]);
                return EXIT_FAILURE;
        }

        if (!strcmp(clockname, "nic")) {
                int fd;
                clockid_t clkid;
                const char *devicename = "/dev/ptp0";

                fd = open(devicename, O_RDWR);
                if (fd < 0) {
                        (void)fprintf(stderr, "opening %s: %s\n", devicename,
                                strerror(errno));
                        return(EXIT_FAILURE);
                }

                clkid = get_clockid(fd);
                if (CLOCK_INVALID == clkid) {
                        (void)fprintf(stderr, "failed to read clock id\n");
                        return(EXIT_FAILURE);
                }

                (void)printf("## test run using nic clock\n");
                test_loop_on_clock(clkid, NUM_TESTRUNS);

                (void)close(fd);
EOF

                typeset i
                for i in "${!ar[@]}" ; do
                        typeset name="${ar[$i].name}"
                        printf '\t} else if (!strcmp(clockname, "%s")) {\n' "$name"
                        printf '\t\t(void)printf("## test run using %s\\n");\n' "$name"
                        printf '\n'
                        printf '\t\ttest_loop_on_clock(%s, NUM_TESTRUNS);\n' "$name"
                done

                cat <<EOF
        } else {
                (void)fprintf(stderr, "%s: Unknown clockname argument %s\n",
                        av[0], clockname);
                return EXIT_FAILURE;
        }

        (void)puts("# end.");

        return(EXIT_SUCCESS);
}
EOF
        } >"generated_count_timer_syscalls.c"

        return 0
}

function compile_test_code
{
        set -o errexit

        printf $"## Compiling test code...\n"

        clang -m32 -g -Wall -Wextra \
                -o generated_count_timer_syscalls \
                generated_count_timer_syscalls.c

        return 0
}

function run_tests
{
        nameref ar="$1"
        compound cmd
        typeset cmd.output
        integer cmd.exit_code
        typeset i

        printf $"## Running tests...\n"

        for i in "${!ar[@]}" ; do
                nameref n=ar["$i"]

                printf $"Probing %q...\n" "${n.name}"
                cmd.output="${ strace ./generated_count_timer_syscalls "${n.name}" 2>&1 ; cmd.exit_code="$?" ; }"

                integer n.num_syscalls_clock_gettime="${ egrep 'clock_gettime' <<<"${cmd.output}" | wc -l ;}"
                integer n.num_syscalls_total="${ wc -l <<<"${cmd.output}" ; }"
                integer n.exit_code=${cmd.exit_code}
        done
}

function print_results
{
        nameref c=$1

        set -o nounset

        printf $"## Raw test results:\n"
        print -v c

        printf $"## Summary of test results for %q:\n" "${c.uname}"
        nameref ar="c.clock_names"
        for i in "${!ar[@]}" ; do
                nameref n=ar["$i"]

                printf $"Clock name %-20s \t" ${n.name}
                if (( (n.exit_code != 0) || (n.num_syscalls_total < 30) )) ; then
                        printf $"TEST FAILED\n"
                elif (( n.num_syscalls_clock_gettime >= c.num_testruns )) ; then
                        printf $"uses traditional syscalls\n"
                elif (( n.num_syscalls_clock_gettime <= 1 )) ; then
                        printf $"uses shortcut\n"
                else
                        printf $"Data inconclusive\n"
                fi
        done
        return 0
}

function main
{
        compound c
        compound -A c.clock_names

        integer c.num_testruns=32100
        typeset c.uname="$(uname -a)"
        typeset c.hostname="$(hostname)"

        if ! enumerate_clock_sources c.clock_names ; then
                print -u2 -f $"%s: Could not enumerate clock names.\n" "$1"
                return 1
        fi

        if ! generate_test_code c.clock_names ${c.num_testruns} ; then
                print -u2 -f $"%s: Could not generate test code.\n" "$1"
                return 1
        fi

        if ! compile_test_code ; then
                print -u2 -f $"%s: Could not compile test code.\n" "$1"
                return 1
        fi

        run_tests c.clock_names

        print_results c

        print $"## Done."
        return 0
}

main "$@"
# EOF.