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selftests/proc: Assert clock_gettime(CLOCK_BOOTTIME) VS /proc/uptime monotonicity

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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
This commit is contained in:
Frederic Weisbecker 2023-02-22 15:46:49 +01:00 • committed by Thomas Gleixner
parent 270b2a679e
commit 263dda24ff
3 changed files with 47 additions and 8 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

21
tools/testing/selftests/proc/proc-uptime-001.c
View file

@ -13,9 +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 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()
// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
// 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>
@ -27,7 +27,7 @@
int main(void)
{
uint64_t start, u0, u1;
uint64_t start, u0, u1, c0, c1;
int fd;
fd = open("/proc/uptime", O_RDONLY);
@ -35,10 +35,23 @@ int main(void)
u0 = proc_uptime(fd);
start = u0;
c0 = clock_boottime();
do {
u1 = proc_uptime(fd);
c1 = clock_boottime();
/* Is /proc/uptime monotonic ? */
assert(u1 >= u0);
/* Is CLOCK_BOOTTIME monotonic ? */
assert(c1 >= c0);
/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
assert(c0 >= u0);
u0 = u1;
c0 = c1;
} while (u1 - start < 100);
return 0;

22
tools/testing/selftests/proc/proc-uptime-002.c
View file

@ -13,9 +13,10 @@
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
// 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()
// Test that boottime value in /proc/uptime and CLOCK_BOOTTIME increment
// 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>
@ -43,10 +44,10 @@ static inline int sys_sched_setaffinity(pid_t pid, unsigned int len, unsigned lo
int main(void)
{
uint64_t u0, u1, c0, c1;
unsigned int len;
unsigned long *m;
unsigned int cpu;
uint64_t u0, u1;
int fd;
/* find out "nr_cpu_ids" */
@ -62,6 +63,8 @@ int main(void)
assert(fd >= 0);
u0 = proc_uptime(fd);
c0 = clock_boottime();
for (cpu = 0; cpu < len * 8; cpu++) {
memset(m, 0, len);
m[cpu / (8 * sizeof(unsigned long))] |= 1UL << (cpu % (8 * sizeof(unsigned long)));
@ -70,8 +73,19 @@ int main(void)
sys_sched_setaffinity(0, len, m);
u1 = proc_uptime(fd);
c1 = clock_boottime();
/* Is /proc/uptime monotonic ? */
assert(u1 >= u0);
/* Is CLOCK_BOOTTIME monotonic ? */
assert(c1 >= c0);
/* Is CLOCK_BOOTTIME VS /proc/uptime monotonic ? */
assert(c0 >= u0);
u0 = u1;
c0 = c1;
}
return 0;

12
tools/testing/selftests/proc/proc-uptime.h
View file

@ -19,9 +19,21 @@
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include "proc.h"
static uint64_t clock_boottime(void)
{
struct timespec ts;
int err;
err = clock_gettime(CLOCK_BOOTTIME, &ts);
assert(err >= 0);
return (ts.tv_sec * 100) + (ts.tv_nsec / 10000000);
}
static uint64_t proc_uptime(int fd)
{
uint64_t val1, val2;