A bunch of fixes that don't need to be on the urgent queue since
they are not regression fixes. But they are still fixes...
Frederic Weisbecker (2):
timers/nohz: Last resort update jiffies on nohz_full IRQ entry
sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full
include/linux/sched/cputime.h | 5 +++--
kernel/sched/cputime.c | 12 +++++++++---
kernel/softirq.c | 3 ++-
kernel/time/tick-sched.c | 7 +++++++
4 files changed, 21 insertions(+), 6 deletions(-)
--
2.25.1
getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime
than the actual time.
task_cputime_adjusted() snapshots utime and stime and then adjust their
sum to match the scheduler maintained cputime.sum_exec_runtime.
Unfortunately in nohz_full, sum_exec_runtime is only updated once per
second in the worst case, causing a discrepancy against utime and stime
that can be updated anytime by the reader using vtime.
To fix this situation, perform an update of cputime.sum_exec_runtime
when the cputime snapshot reports the task as actually running while
the tick is disabled. The related overhead is then contained within the
relevant situations.
Reported-by: Hasegawa Hitomi <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Hasegawa Hitomi <[email protected]>
---
include/linux/sched/cputime.h | 5 +++--
kernel/sched/cputime.c | 12 +++++++++---
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
index 6c9f19a33865..ce3c58286062 100644
--- a/include/linux/sched/cputime.h
+++ b/include/linux/sched/cputime.h
@@ -18,15 +18,16 @@
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-extern void task_cputime(struct task_struct *t,
+extern bool task_cputime(struct task_struct *t,
u64 *utime, u64 *stime);
extern u64 task_gtime(struct task_struct *t);
#else
-static inline void task_cputime(struct task_struct *t,
+static inline bool task_cputime(struct task_struct *t,
u64 *utime, u64 *stime)
{
*utime = t->utime;
*stime = t->stime;
+ return false;
}
static inline u64 task_gtime(struct task_struct *t)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 872e481d5098..9392aea1804e 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -615,7 +615,8 @@ void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
.sum_exec_runtime = p->se.sum_exec_runtime,
};
- task_cputime(p, &cputime.utime, &cputime.stime);
+ if (task_cputime(p, &cputime.utime, &cputime.stime))
+ cputime.sum_exec_runtime = task_sched_runtime(p);
cputime_adjust(&cputime, &p->prev_cputime, ut, st);
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
@@ -828,19 +829,21 @@ u64 task_gtime(struct task_struct *t)
* add up the pending nohz execution time since the last
* cputime snapshot.
*/
-void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
+bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
{
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 delta;
+ int ret;
if (!vtime_accounting_enabled()) {
*utime = t->utime;
*stime = t->stime;
- return;
+ return false;
}
do {
+ ret = false;
seq = read_seqcount_begin(&vtime->seqcount);
*utime = t->utime;
@@ -850,6 +853,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
if (vtime->state < VTIME_SYS)
continue;
+ ret = true;
delta = vtime_delta(vtime);
/*
@@ -861,6 +865,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
else
*utime += vtime->utime + delta;
} while (read_seqcount_retry(&vtime->seqcount, seq));
+
+ return ret;
}
static int vtime_state_fetch(struct vtime *vtime, int cpu)
--
2.25.1
On Tue, Oct 26, 2021 at 04:10:55PM +0200, Frederic Weisbecker wrote:
> getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime
> than the actual time.
>
> task_cputime_adjusted() snapshots utime and stime and then adjust their
> sum to match the scheduler maintained cputime.sum_exec_runtime.
> Unfortunately in nohz_full, sum_exec_runtime is only updated once per
> second in the worst case, causing a discrepancy against utime and stime
> that can be updated anytime by the reader using vtime.
>
> To fix this situation, perform an update of cputime.sum_exec_runtime
> when the cputime snapshot reports the task as actually running while
> the tick is disabled. The related overhead is then contained within the
> relevant situations.
>
> Reported-by: Hasegawa Hitomi <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Mel Gorman <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Signed-off-by: Hasegawa Hitomi <[email protected]>
Thank you for this patch. getrusage(RUSAGE_THREAD) with nohz_full works well!
Please feel free to add:
Tested-by: Masayoshi Mizuma <[email protected]>
Thanks,
Masa
> ---
> include/linux/sched/cputime.h | 5 +++--
> kernel/sched/cputime.c | 12 +++++++++---
> 2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
> index 6c9f19a33865..ce3c58286062 100644
> --- a/include/linux/sched/cputime.h
> +++ b/include/linux/sched/cputime.h
> @@ -18,15 +18,16 @@
> #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
>
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
> -extern void task_cputime(struct task_struct *t,
> +extern bool task_cputime(struct task_struct *t,
> u64 *utime, u64 *stime);
> extern u64 task_gtime(struct task_struct *t);
> #else
> -static inline void task_cputime(struct task_struct *t,
> +static inline bool task_cputime(struct task_struct *t,
> u64 *utime, u64 *stime)
> {
> *utime = t->utime;
> *stime = t->stime;
> + return false;
> }
>
> static inline u64 task_gtime(struct task_struct *t)
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 872e481d5098..9392aea1804e 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -615,7 +615,8 @@ void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
> .sum_exec_runtime = p->se.sum_exec_runtime,
> };
>
> - task_cputime(p, &cputime.utime, &cputime.stime);
> + if (task_cputime(p, &cputime.utime, &cputime.stime))
> + cputime.sum_exec_runtime = task_sched_runtime(p);
> cputime_adjust(&cputime, &p->prev_cputime, ut, st);
> }
> EXPORT_SYMBOL_GPL(task_cputime_adjusted);
> @@ -828,19 +829,21 @@ u64 task_gtime(struct task_struct *t)
> * add up the pending nohz execution time since the last
> * cputime snapshot.
> */
> -void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> +bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> {
> struct vtime *vtime = &t->vtime;
> unsigned int seq;
> u64 delta;
> + int ret;
>
> if (!vtime_accounting_enabled()) {
> *utime = t->utime;
> *stime = t->stime;
> - return;
> + return false;
> }
>
> do {
> + ret = false;
> seq = read_seqcount_begin(&vtime->seqcount);
>
> *utime = t->utime;
> @@ -850,6 +853,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> if (vtime->state < VTIME_SYS)
> continue;
>
> + ret = true;
> delta = vtime_delta(vtime);
>
> /*
> @@ -861,6 +865,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> else
> *utime += vtime->utime + delta;
> } while (read_seqcount_retry(&vtime->seqcount, seq));
> +
> + return ret;
> }
>
> static int vtime_state_fetch(struct vtime *vtime, int cpu)
> --
> 2.25.1
>
Hi,
On Tue, Oct 26, 2021 at 04:10:55PM +0200 Frederic Weisbecker wrote:
> getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime
> than the actual time.
>
> task_cputime_adjusted() snapshots utime and stime and then adjust their
> sum to match the scheduler maintained cputime.sum_exec_runtime.
> Unfortunately in nohz_full, sum_exec_runtime is only updated once per
> second in the worst case, causing a discrepancy against utime and stime
> that can be updated anytime by the reader using vtime.
>
> To fix this situation, perform an update of cputime.sum_exec_runtime
> when the cputime snapshot reports the task as actually running while
> the tick is disabled. The related overhead is then contained within the
> relevant situations.
>
> Reported-by: Hasegawa Hitomi <[email protected]>
> Signed-off-by: Frederic Weisbecker <[email protected]>
> Cc: Mel Gorman <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Signed-off-by: Hasegawa Hitomi <[email protected]>
> ---
> include/linux/sched/cputime.h | 5 +++--
> kernel/sched/cputime.c | 12 +++++++++---
> 2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
> index 6c9f19a33865..ce3c58286062 100644
> --- a/include/linux/sched/cputime.h
> +++ b/include/linux/sched/cputime.h
> @@ -18,15 +18,16 @@
> #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
>
> #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
> -extern void task_cputime(struct task_struct *t,
> +extern bool task_cputime(struct task_struct *t,
> u64 *utime, u64 *stime);
> extern u64 task_gtime(struct task_struct *t);
> #else
> -static inline void task_cputime(struct task_struct *t,
> +static inline bool task_cputime(struct task_struct *t,
> u64 *utime, u64 *stime)
> {
> *utime = t->utime;
> *stime = t->stime;
> + return false;
> }
>
> static inline u64 task_gtime(struct task_struct *t)
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 872e481d5098..9392aea1804e 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -615,7 +615,8 @@ void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
> .sum_exec_runtime = p->se.sum_exec_runtime,
> };
>
> - task_cputime(p, &cputime.utime, &cputime.stime);
> + if (task_cputime(p, &cputime.utime, &cputime.stime))
> + cputime.sum_exec_runtime = task_sched_runtime(p);
> cputime_adjust(&cputime, &p->prev_cputime, ut, st);
> }
> EXPORT_SYMBOL_GPL(task_cputime_adjusted);
> @@ -828,19 +829,21 @@ u64 task_gtime(struct task_struct *t)
> * add up the pending nohz execution time since the last
> * cputime snapshot.
> */
> -void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> +bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> {
> struct vtime *vtime = &t->vtime;
> unsigned int seq;
> u64 delta;
> + int ret;
>
> if (!vtime_accounting_enabled()) {
> *utime = t->utime;
> *stime = t->stime;
> - return;
> + return false;
> }
>
> do {
> + ret = false;
> seq = read_seqcount_begin(&vtime->seqcount);
>
> *utime = t->utime;
> @@ -850,6 +853,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> if (vtime->state < VTIME_SYS)
> continue;
>
> + ret = true;
> delta = vtime_delta(vtime);
>
> /*
> @@ -861,6 +865,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
> else
> *utime += vtime->utime + delta;
> } while (read_seqcount_retry(&vtime->seqcount, seq));
> +
> + return ret;
> }
>
> static int vtime_state_fetch(struct vtime *vtime, int cpu)
> --
> 2.25.1
>
Could someone please pick this (or, rather, these) up?
Acked-by: Phil Auld <[email protected]>
Thanks!
Phil
--
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: e7f2be115f0746b969c0df14c0d182f65f005ca5
Gitweb: https://git.kernel.org/tip/e7f2be115f0746b969c0df14c0d182f65f005ca5
Author: Frederic Weisbecker <[email protected]>
AuthorDate: Tue, 26 Oct 2021 16:10:55 +02:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Thu, 02 Dec 2021 15:08:22 +01:00
sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full
getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime
than the actual time.
task_cputime_adjusted() snapshots utime and stime and then adjust their
sum to match the scheduler maintained cputime.sum_exec_runtime.
Unfortunately in nohz_full, sum_exec_runtime is only updated once per
second in the worst case, causing a discrepancy against utime and stime
that can be updated anytime by the reader using vtime.
To fix this situation, perform an update of cputime.sum_exec_runtime
when the cputime snapshot reports the task as actually running while
the tick is disabled. The related overhead is then contained within the
relevant situations.
Reported-by: Hasegawa Hitomi <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Hasegawa Hitomi <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Masayoshi Mizuma <[email protected]>
Acked-by: Phil Auld <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
include/linux/sched/cputime.h | 5 +++--
kernel/sched/cputime.c | 12 +++++++++---
2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h
index 6c9f19a..ce3c582 100644
--- a/include/linux/sched/cputime.h
+++ b/include/linux/sched/cputime.h
@@ -18,15 +18,16 @@
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-extern void task_cputime(struct task_struct *t,
+extern bool task_cputime(struct task_struct *t,
u64 *utime, u64 *stime);
extern u64 task_gtime(struct task_struct *t);
#else
-static inline void task_cputime(struct task_struct *t,
+static inline bool task_cputime(struct task_struct *t,
u64 *utime, u64 *stime)
{
*utime = t->utime;
*stime = t->stime;
+ return false;
}
static inline u64 task_gtime(struct task_struct *t)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 872e481..9392aea 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -615,7 +615,8 @@ void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
.sum_exec_runtime = p->se.sum_exec_runtime,
};
- task_cputime(p, &cputime.utime, &cputime.stime);
+ if (task_cputime(p, &cputime.utime, &cputime.stime))
+ cputime.sum_exec_runtime = task_sched_runtime(p);
cputime_adjust(&cputime, &p->prev_cputime, ut, st);
}
EXPORT_SYMBOL_GPL(task_cputime_adjusted);
@@ -828,19 +829,21 @@ u64 task_gtime(struct task_struct *t)
* add up the pending nohz execution time since the last
* cputime snapshot.
*/
-void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
+bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
{
struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 delta;
+ int ret;
if (!vtime_accounting_enabled()) {
*utime = t->utime;
*stime = t->stime;
- return;
+ return false;
}
do {
+ ret = false;
seq = read_seqcount_begin(&vtime->seqcount);
*utime = t->utime;
@@ -850,6 +853,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
if (vtime->state < VTIME_SYS)
continue;
+ ret = true;
delta = vtime_delta(vtime);
/*
@@ -861,6 +865,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
else
*utime += vtime->utime + delta;
} while (read_seqcount_retry(&vtime->seqcount, seq));
+
+ return ret;
}
static int vtime_state_fetch(struct vtime *vtime, int cpu)