Messages in this thread Patch in this message | | | From | Liu Chao <> | Subject | [PATCH v2] add miss time to CPUTIME_USER when kernel boots with highres=off | Date | Mon, 1 Aug 2022 09:21:07 +0800 |
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When kernel boots with highres=off and the cpu load isn't full, almost every tick will account towards CPUTIME_IDLE. But in /proc/stat, idle time is obtained from get_idle_time. So the sum time will lose the time of user tasks.
For example: # stress-ng --cpu 2 --taskset 66 --timeout 600 --cpu-load 50 & # cat /proc/stat | grep "cpu66";sleep 10; cat /proc/stat | grep "cpu66" cpu66 1038 0 72 50124 75 17 1 0 0 0 cpu66 1038 0 72 50569 75 18 2 0 0 0
the detla of sum time is 447, which should be 1000 actually. It will casue the data in top is imprecise.
v2: Fix build error when CONFIG_HIGH_RES_TIMERS is not set.
Signed-off-by: Liu Chao <liuchao173@huawei.com> --- fs/proc/stat.c | 5 +++++ include/linux/hrtimer.h | 2 ++ kernel/time/hrtimer.c | 4 ++-- 3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/proc/stat.c b/fs/proc/stat.c index 4fb8729a68d4..c5b9116e74ad 100644 --- a/fs/proc/stat.c +++ b/fs/proc/stat.c @@ -141,6 +141,9 @@ static int show_stat(struct seq_file *p, void *v) sum += kstat_cpu_irqs_sum(i); sum += arch_irq_stat_cpu(i); + if (hrtimer_is_hres_enabled() == 0) + user += cpustat[CPUTIME_IDLE] - get_idle_time(&kcpustat, i); + for (j = 0; j < NR_SOFTIRQS; j++) { unsigned int softirq_stat = kstat_softirqs_cpu(j, i); @@ -179,6 +182,8 @@ static int show_stat(struct seq_file *p, void *v) steal = cpustat[CPUTIME_STEAL]; guest = cpustat[CPUTIME_GUEST]; guest_nice = cpustat[CPUTIME_GUEST_NICE]; + if (hrtimer_is_hres_enabled() == 0) + user += cpustat[CPUTIME_IDLE] - idle; seq_printf(p, "cpu%d", i); seq_put_decimal_ull(p, " ", nsec_to_clock_t(user)); seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice)); diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 0ee140176f10..4fa1bbe86287 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -326,6 +326,8 @@ extern unsigned int hrtimer_resolution; #endif +extern int hrtimer_is_hres_enabled(void); + static inline ktime_t __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now) { diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 0ea8702eb516..3e038b28b8db 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -722,7 +722,7 @@ __setup("highres=", setup_hrtimer_hres); /* * hrtimer_high_res_enabled - query, if the highres mode is enabled */ -static inline int hrtimer_is_hres_enabled(void) +int hrtimer_is_hres_enabled(void) { return hrtimer_hres_enabled; } @@ -751,7 +751,7 @@ static void hrtimer_switch_to_hres(void) #else -static inline int hrtimer_is_hres_enabled(void) { return 0; } +int hrtimer_is_hres_enabled(void) { return 0; } static inline void hrtimer_switch_to_hres(void) { } #endif /* CONFIG_HIGH_RES_TIMERS */ base-commit: e65c6a46df94c8d76ea1129eb2d4564670c6f214 prerequisite-patch-id: 3099d45f464060b03429daa159ee8d882d113edc prerequisite-patch-id: db6e0da8d4379352a3bd819eb158f78e66abf01d -- 2.23.0
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