by tip-bot2 for Alexey Makhalov

[permalink] [raw]

Subject: [tip: timers/core] selftests/proc: Assert clock_gettime(CLOCK_BOOTTIME) VS /proc/uptime monotonicity

The following commit has been merged into the timers/core branch of tip:

Commit-ID: 263dda24fff0957f6b0a9abde2809122f7f0fad8
Gitweb: https://git.kernel.org/tip/263dda24fff0957f6b0a9abde2809122f7f0fad8
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Wed, 22 Feb 2023 15:46:49 +01:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Tue, 18 Apr 2023 16:35:13 +02:00

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

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 <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

---
tools/testing/selftests/proc/proc-uptime-001.c | 21 ++++++++++++----
tools/testing/selftests/proc/proc-uptime-002.c | 22 +++++++++++++----
tools/testing/selftests/proc/proc-uptime.h | 12 +++++++++-
3 files changed, 47 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/proc/proc-uptime-001.c b/tools/testing/selftests/proc/proc-uptime-001.c
index 35bddd9..f335eec 100644
--- a/tools/testing/selftests/proc/proc-uptime-001.c
+++ b/tools/testing/selftests/proc/proc-uptime-001.c
@@ -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;
diff --git a/tools/testing/selftests/proc/proc-uptime-002.c b/tools/testing/selftests/proc/proc-uptime-002.c
index 7ad79d5..ae453da 100644
--- a/tools/testing/selftests/proc/proc-uptime-002.c
+++ b/tools/testing/selftests/proc/proc-uptime-002.c
@@ -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;
diff --git a/tools/testing/selftests/proc/proc-uptime.h b/tools/testing/selftests/proc/proc-uptime.h
index ca55abe..730cce4 100644
--- a/tools/testing/selftests/proc/proc-uptime.h
+++ b/tools/testing/selftests/proc/proc-uptime.h
@@ -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;

2023-04-18 14:55:14

by tip-bot2 for Alexey Makhalov

[permalink] [raw]

Subject: [tip: timers/core] timers/nohz: Restructure and reshuffle struct tick_sched

The following commit has been merged into the timers/core branch of tip:

Commit-ID: 605da849d5982dee0527edb2488b79795f31a150
Gitweb: https://git.kernel.org/tip/605da849d5982dee0527edb2488b79795f31a150
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Wed, 22 Feb 2023 15:46:42 +01:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Tue, 18 Apr 2023 16:35:12 +02:00

timers/nohz: Restructure and reshuffle struct tick_sched

Restructure and group fields by access in order to optimize cache
layout. While at it, also add missing kernel doc for two fields:
@last_jiffies and @idle_expires.

Reported-by: Thomas Gleixner <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

---
kernel/time/tick-sched.h | 66 ++++++++++++++++++++++++---------------
1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index 5046495..c666325 100644
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -22,65 +22,81 @@ enum tick_nohz_mode {

/**
* struct tick_sched - sched tick emulation and no idle tick control/stats
- * @sched_timer: hrtimer to schedule the periodic tick in high
- * resolution mode
- * @check_clocks: Notification mechanism about clocksource changes
- * @nohz_mode: Mode - one state of tick_nohz_mode
+ *
* @inidle: Indicator that the CPU is in the tick idle mode
* @tick_stopped: Indicator that the idle tick has been stopped
* @idle_active: Indicator that the CPU is actively in the tick idle mode;
* it is reset during irq handling phases.
- * @do_timer_lst: CPU was the last one doing do_timer before going idle
+ * @do_timer_last: CPU was the last one doing do_timer before going idle
* @got_idle_tick: Tick timer function has run with @inidle set
+ * @stalled_jiffies: Number of stalled jiffies detected across ticks
+ * @last_tick_jiffies: Value of jiffies seen on last tick
+ * @sched_timer: hrtimer to schedule the periodic tick in high
+ * resolution mode
* @last_tick: Store the last tick expiry time when the tick
* timer is modified for nohz sleeps. This is necessary
* to resume the tick timer operation in the timeline
* when the CPU returns from nohz sleep.
* @next_tick: Next tick to be fired when in dynticks mode.
* @idle_jiffies: jiffies at the entry to idle for idle time accounting
+ * @idle_waketime: Time when the idle was interrupted
+ * @idle_entrytime: Time when the idle call was entered
+ * @nohz_mode: Mode - one state of tick_nohz_mode
+ * @last_jiffies: Base jiffies snapshot when next event was last computed
+ * @timer_expires_base: Base time clock monotonic for @timer_expires
+ * @timer_expires: Anticipated timer expiration time (in case sched tick is stopped)
+ * @next_timer: Expiry time of next expiring timer for debugging purpose only
+ * @idle_expires: Next tick in idle, for debugging purpose only
* @idle_calls: Total number of idle calls
* @idle_sleeps: Number of idle calls, where the sched tick was stopped
- * @idle_entrytime: Time when the idle call was entered
- * @idle_waketime: Time when the idle was interrupted
* @idle_exittime: Time when the idle state was left
* @idle_sleeptime: Sum of the time slept in idle with sched tick stopped
* @iowait_sleeptime: Sum of the time slept in idle with sched tick stopped, with IO outstanding
- * @timer_expires: Anticipated timer expiration time (in case sched tick is stopped)
- * @timer_expires_base: Base time clock monotonic for @timer_expires
- * @next_timer: Expiry time of next expiring timer for debugging purpose only
* @tick_dep_mask: Tick dependency mask - is set, if someone needs the tick
- * @last_tick_jiffies: Value of jiffies seen on last tick
- * @stalled_jiffies: Number of stalled jiffies detected across ticks
+ * @check_clocks: Notification mechanism about clocksource changes
*/
struct tick_sched {
- struct hrtimer sched_timer;
- unsigned long check_clocks;
- enum tick_nohz_mode nohz_mode;
-
+ /* Common flags */
unsigned int inidle : 1;
unsigned int tick_stopped : 1;
unsigned int idle_active : 1;
unsigned int do_timer_last : 1;
unsigned int got_idle_tick : 1;

+ /* Tick handling: jiffies stall check */
+ unsigned int stalled_jiffies;
+ unsigned long last_tick_jiffies;
+
+ /* Tick handling */
+ struct hrtimer sched_timer;
ktime_t last_tick;
ktime_t next_tick;
unsigned long idle_jiffies;
- unsigned long idle_calls;
- unsigned long idle_sleeps;
- ktime_t idle_entrytime;
ktime_t idle_waketime;
- ktime_t idle_exittime;
- ktime_t idle_sleeptime;
- ktime_t iowait_sleeptime;
+
+ /* Idle entry */
+ ktime_t idle_entrytime;
+
+ /* Tick stop */
+ enum tick_nohz_mode nohz_mode;
unsigned long last_jiffies;
- u64 timer_expires;
u64 timer_expires_base;
+ u64 timer_expires;
u64 next_timer;
ktime_t idle_expires;
+ unsigned long idle_calls;
+ unsigned long idle_sleeps;
+
+ /* Idle exit */
+ ktime_t idle_exittime;
+ ktime_t idle_sleeptime;
+ ktime_t iowait_sleeptime;
+
+ /* Full dynticks handling */
atomic_t tick_dep_mask;
- unsigned long last_tick_jiffies;
- unsigned int stalled_jiffies;
+
+ /* Clocksource changes */
+ unsigned long check_clocks;
};

extern struct tick_sched *tick_get_tick_sched(int cpu);