The following commit has been merged into the timers/core branch of tip:
Commit-ID: 270b2a679ea7be1ee2d84ea67751fb1ab15bcb20
Gitweb: https://git.kernel.org/tip/270b2a679ea7be1ee2d84ea67751fb1ab15bcb20
Author: Frederic Weisbecker <frederic@kernel.org>
AuthorDate: Wed, 22 Feb 2023 15:46:48 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 18 Apr 2023 16:35:13 +02:00
selftests/proc: Remove idle time monotonicity assertions
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
---
tools/testing/selftests/proc/proc-uptime-001.c | 12 ++++++------
tools/testing/selftests/proc/proc-uptime-002.c | 13 ++++++-------
tools/testing/selftests/proc/proc-uptime.h | 16 ++--------------
3 files changed, 14 insertions(+), 27 deletions(-)
@@ -13,7 +13,9 @@
* 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.
+// Test that boottime value in /proc/uptime increments monotonically.
+// We don't test idle time monotonicity due to broken iowait task
+// counting, cf: comment above get_cpu_idle_time_us()
#undef NDEBUG
#include <assert.h>
#include <stdint.h>
@@ -25,20 +27,18 @@
int main(void)
{
- uint64_t start, u0, u1, i0, i1;
+ uint64_t start, u0, u1;
int fd;
fd = open("/proc/uptime", O_RDONLY);
assert(fd >= 0);
- proc_uptime(fd, &u0, &i0);
+ u0 = proc_uptime(fd);
start = u0;
do {
- proc_uptime(fd, &u1, &i1);
+ u1 = proc_uptime(fd);
assert(u1 >= u0);
- assert(i1 >= i0);
u0 = u1;
- i0 = i1;
} while (u1 - start < 100);
return 0;
@@ -13,8 +13,9 @@
* 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.
+// Test that boottime value in /proc/uptime increments monotonically
+// while shifting across CPUs. We don't test idle time monotonicity
+// due to broken iowait task counting, cf: comment above get_cpu_idle_time_us()
#undef NDEBUG
#include <assert.h>
#include <errno.h>
@@ -45,7 +46,7 @@ int main(void)
unsigned int len;
unsigned long *m;
unsigned int cpu;
- uint64_t u0, u1, i0, i1;
+ uint64_t u0, u1;
int fd;
/* find out "nr_cpu_ids" */
@@ -60,7 +61,7 @@ int main(void)
fd = open("/proc/uptime", O_RDONLY);
assert(fd >= 0);
- proc_uptime(fd, &u0, &i0);
+ u0 = proc_uptime(fd);
for (cpu = 0; cpu < len * 8; cpu++) {
memset(m, 0, len);
m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
@@ -68,11 +69,9 @@ int main(void)
/* CPU might not exist, ignore error */
sys_sched_setaffinity(0, len, m);
- proc_uptime(fd, &u1, &i1);
+ u1 = proc_uptime(fd);
assert(u1 >= u0);
- assert(i1 >= i0);
u0 = u1;
- i0 = i1;
}
return 0;
@@ -22,7 +22,7 @@
#include "proc.h"
-static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
+static uint64_t proc_uptime(int fd)
{
uint64_t val1, val2;
char buf[64], *p;
@@ -43,18 +43,6 @@ static void proc_uptime(int fd, uint64_t *uptime, uint64_t *idle)
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);
+ return val1 * 100 + val2;
}