On Mon, Feb 20, 2023 at 10:53:17PM +0100, Thomas Gleixner wrote:
> On Mon, Feb 20 2023 at 13:41, Frederic Weisbecker wrote:
>
> > 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 selftests 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>
>
> I did really not ask you to remove the selftests alltogether.
>
> Those tests check uptime and idle time. I asked you to remove the idle
> time monotonicity assertion.
>
> uptime is really supposed to be monotonically increasing. It's based on
> CLOCK_BOOTTIME. If that goes backwards then we surely have more trouble
> than /proc/uptime.
Right, I naively thought it wasn't worth checking CLOCK_BOOTTIME monotonicity
alone... Anyway, kept that in the new version.
>
> But it would be a good thing to change the test in the following way:
>
> ut1 = parse("/proc/uptime");
> bt1 = clock_gettime(CLOCK_BOOTTIME);
> assert(ut1 <= bt1);
> ut2 = parse("/proc/uptime");
> bt2 = clock_gettime(CLOCK_BOOTTIME);
> assert(ut2 <= bt2);
> assert(ut1 <= ut2);
> ....
>
> Hmm?
Makes sense, added to the new version.
Thanks!
>
> Thanks,
>
> tglx
@@ -13,8 +13,6 @@
/proc-self-wchan
/proc-subset-pid
/proc-tid0
-/proc-uptime-001
-/proc-uptime-002
/read
/self
/setns-dcache
@@ -16,8 +16,6 @@ TEST_GEN_PROGS += proc-self-syscall
TEST_GEN_PROGS += proc-self-wchan
TEST_GEN_PROGS += proc-subset-pid
TEST_GEN_PROGS += proc-tid0
-TEST_GEN_PROGS += proc-uptime-001
-TEST_GEN_PROGS += proc-uptime-002
TEST_GEN_PROGS += read
TEST_GEN_PROGS += self
TEST_GEN_PROGS += setns-dcache
deleted file mode 100644
@@ -1,45 +0,0 @@
-/*
- * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-// Test that values in /proc/uptime increment monotonically.
-#undef NDEBUG
-#include <assert.h>
-#include <stdint.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-
-#include "proc-uptime.h"
-
-int main(void)
-{
- uint64_t start, u0, u1, i0, i1;
- int fd;
-
- fd = open("/proc/uptime", O_RDONLY);
- assert(fd >= 0);
-
- proc_uptime(fd, &u0, &i0);
- start = u0;
- do {
- proc_uptime(fd, &u1, &i1);
- assert(u1 >= u0);
- assert(i1 >= i0);
- u0 = u1;
- i0 = i1;
- } while (u1 - start < 100);
-
- return 0;
-}
deleted file mode 100644
@@ -1,79 +0,0 @@
-/*
- * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-// Test that values in /proc/uptime increment monotonically
-// while shifting across CPUs.
-#undef NDEBUG
-#include <assert.h>
-#include <errno.h>
-#include <unistd.h>
-#include <sys/syscall.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <stdint.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-
-#include "proc-uptime.h"
-
-static inline int sys_sched_getaffinity(pid_t pid, unsigned int len, unsigned long *m)
-{
- return syscall(SYS_sched_getaffinity, pid, len, m);
-}
-
-static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned long *m)
-{
- return syscall(SYS_sched_setaffinity, pid, len, m);
-}
-
-int main(void)
-{
- unsigned int len;
- unsigned long *m;
- unsigned int cpu;
- uint64_t u0, u1, i0, i1;
- int fd;
-
- /* find out "nr_cpu_ids" */
- m = NULL;
- len = 0;
- do {
- len += sizeof(unsigned long);
- free(m);
- m = malloc(len);
- } while (sys_sched_getaffinity(0, len, m) == -1 && errno == EINVAL);
-
- fd = open("/proc/uptime", O_RDONLY);
- assert(fd >= 0);
-
- proc_uptime(fd, &u0, &i0);
- for (cpu = 0; cpu < len * 8; cpu++) {
- memset(m, 0, len);
- m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
-
- /* CPU might not exist, ignore error */
- sys_sched_setaffinity(0, len, m);
-
- proc_uptime(fd, &u1, &i1);
- assert(u1 >= u0);
- assert(i1 >= i0);
- u0 = u1;
- i0 = i1;
- }
-
- return 0;
-}
deleted file mode 100644
@@ -1,60 +0,0 @@
-/*
- * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-#undef NDEBUG
-#include <assert.h>
-#include <errno.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-
-#include "proc.h"
-
-static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
-{
- uint64_t val1, val2;
- char buf[64], *p;
- ssize_t rv;
-
- /* save "p < end" checks */
- memset(buf, 0, sizeof(buf));
- rv = pread(fd, buf, sizeof(buf), 0);
- assert(0 <= rv && rv <= sizeof(buf));
- buf[sizeof(buf) - 1] = '\0';
-
- p = buf;
-
- val1 = xstrtoull(p, &p);
- assert(p[0] == '.');
- assert('0' <= p[1] && p[1] <= '9');
- assert('0' <= p[2] && p[2] <= '9');
- assert(p[3] == ' ');
-
- val2 = (p[1] - '0') * 10 + p[2] - '0';
- *uptime = val1 * 100 + val2;
-
- p += 4;
-
- val1 = xstrtoull(p, &p);
- assert(p[0] == '.');
- assert('0' <= p[1] && p[1] <= '9');
- assert('0' <= p[2] && p[2] <= '9');
- assert(p[3] == '\n');
-
- val2 = (p[1] - '0') * 10 + p[2] - '0';
- *idle = val1 * 100 + val2;
-
- assert(p + 4 == buf + rv);
-}