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The first field of /proc/uptime relies on the CLOCK_BOOTTIME clock which can also be fetched from clock_gettime() API. Improve the test coverage while verifying the monotonicity of CLOCK_BOOTTIME accross both interfaces. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20230222144649.624380-9-frederic@kernel.org
59 lines
1.6 KiB
C
59 lines
1.6 KiB
C
/*
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* Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
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// monotonically. We don't test idle time monotonicity due to broken iowait
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// task counting, cf: comment above get_cpu_idle_time_us()
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#undef NDEBUG
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#include <assert.h>
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "proc-uptime.h"
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int main(void)
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{
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uint64_t start, u0, u1, c0, c1;
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int fd;
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fd = open("/proc/uptime", O_RDONLY);
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assert(fd >= 0);
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u0 = proc_uptime(fd);
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start = u0;
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c0 = clock_boottime();
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do {
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u1 = proc_uptime(fd);
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c1 = clock_boottime();
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/* Is /proc/uptime monotonic ? */
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assert(u1 >= u0);
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/* Is CLOCK_BOOTTIME monotonic ? */
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assert(c1 >= c0);
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/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
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assert(c0 >= u0);
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u0 = u1;
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c0 = c1;
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} while (u1 - start < 100);
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return 0;
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}
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