selftests/timens/gettime_perf.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #define _GNU_SOURCE
0003 #include <sys/types.h>
0004 #include <sys/stat.h>
0005 #include <errno.h>
0006 #include <fcntl.h>
0007 #include <sched.h>
0008 #include <time.h>
0009 #include <stdio.h>
0010 #include <unistd.h>
0011 #include <sys/syscall.h>
0012 #include <dlfcn.h>
0013
0014 #include "log.h"
0015 #include "timens.h"
0016
0017 typedef int (*vgettime_t)(clockid_t, struct timespec *);
0018
0019 vgettime_t vdso_clock_gettime;
0020
0021 static void fill_function_pointers(void)
0022 {
0023     void *vdso = dlopen("linux-vdso.so.1",
0024                 RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
0025     if (!vdso)
0026         vdso = dlopen("linux-gate.so.1",
0027                   RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
0028     if (!vdso)
0029         vdso = dlopen("linux-vdso32.so.1",
0030                   RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
0031     if (!vdso)
0032         vdso = dlopen("linux-vdso64.so.1",
0033                   RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
0034     if (!vdso) {
0035         pr_err("[WARN]\tfailed to find vDSO\n");
0036         return;
0037     }
0038
0039     vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
0040     if (!vdso_clock_gettime)
0041         vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__kernel_clock_gettime");
0042     if (!vdso_clock_gettime)
0043         pr_err("Warning: failed to find clock_gettime in vDSO\n");
0044
0045 }
0046
0047 static void test(clock_t clockid, char *clockstr, bool in_ns)
0048 {
0049     struct timespec tp, start;
0050     long i = 0;
0051     const int timeout = 3;
0052
0053     vdso_clock_gettime(clockid, &start);
0054     tp = start;
0055     for (tp = start; start.tv_sec + timeout > tp.tv_sec ||
0056              (start.tv_sec + timeout == tp.tv_sec &&
0057               start.tv_nsec > tp.tv_nsec); i++) {
0058         vdso_clock_gettime(clockid, &tp);
0059     }
0060
0061     ksft_test_result_pass("%s:\tclock: %10s\tcycles:\t%10ld\n",
0062                   in_ns ? "ns" : "host", clockstr, i);
0063 }
0064
0065 int main(int argc, char *argv[])
0066 {
0067     time_t offset = 10;
0068     int nsfd;
0069
0070     ksft_set_plan(8);
0071
0072     fill_function_pointers();
0073
0074     test(CLOCK_MONOTONIC, "monotonic", false);
0075     test(CLOCK_MONOTONIC_COARSE, "monotonic-coarse", false);
0076     test(CLOCK_MONOTONIC_RAW, "monotonic-raw", false);
0077     test(CLOCK_BOOTTIME, "boottime", false);
0078
0079     nscheck();
0080
0081     if (unshare_timens())
0082         return 1;
0083
0084     nsfd = open("/proc/self/ns/time_for_children", O_RDONLY);
0085     if (nsfd < 0)
0086         return pr_perror("Can't open a time namespace");
0087
0088     if (_settime(CLOCK_MONOTONIC, offset))
0089         return 1;
0090     if (_settime(CLOCK_BOOTTIME, offset))
0091         return 1;
0092
0093     if (setns(nsfd, CLONE_NEWTIME))
0094         return pr_perror("setns");
0095
0096     test(CLOCK_MONOTONIC, "monotonic", true);
0097     test(CLOCK_MONOTONIC_COARSE, "monotonic-coarse", true);
0098     test(CLOCK_MONOTONIC_RAW, "monotonic-raw", true);
0099     test(CLOCK_BOOTTIME, "boottime", true);
0100
0101     ksft_exit_pass();
0102     return 0;
0103 }