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270b2a679e
Due to broken iowait task counting design (cf: comments above get_cpu_idle_time_us() and nr_iowait()), it is not possible to provide the guarantee that /proc/stat or /proc/uptime display monotonic idle time values. Remove the assertions that verify the related wrong assumption so that testers and maintainers don't spend more time on that. Reported-by: Yu Liao <liaoyu15@huawei.com> Reported-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/20230222144649.624380-8-frederic@kernel.org
79 lines
2.2 KiB
C
79 lines
2.2 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 increments monotonically
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// while shifting across CPUs. We don't test idle time monotonicity
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// due to broken iowait 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 <errno.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include <stdlib.h>
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#include <string.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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static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
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{
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return syscall(SYS_sched_getaffinity, pid, len, m);
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}
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static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
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{
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return syscall(SYS_sched_setaffinity, pid, len, m);
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}
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int main(void)
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{
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unsigned int len;
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unsigned long *m;
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unsigned int cpu;
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uint64_t u0, u1;
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int fd;
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/* find out "nr_cpu_ids" */
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m = NULL;
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len = 0;
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do {
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len += sizeof(unsigned long);
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free(m);
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m = malloc(len);
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} while (sys_sched_getaffinity(0, len, m) == -1 && errno == EINVAL);
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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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for (cpu = 0; cpu < len * 8; cpu++) {
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memset(m, 0, len);
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m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
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/* CPU might not exist, ignore error */
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sys_sched_setaffinity(0, len, m);
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u1 = proc_uptime(fd);
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assert(u1 >= u0);
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u0 = u1;
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}
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return 0;
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}
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