+ timers-implement-usleep_idle_range.patch added to -mm tree

+ timers-implement-usleep_idle_range.patch added to -mm tree

[akpm]

The patch titled
     Subject: timers: implement usleep_idle_range()
has been added to the -mm tree.  Its filename is
     timers-implement-usleep_idle_range.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/timers-implement-usleep_idle_range.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/timers-implement-usleep_idle_range.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: timers: implement usleep_idle_range()

Patch series "mm/damon: Fix fake /proc/loadavg reports", v3.

This patchset fixes DAMON's fake load report issue.  The first patch makes
yet another variant of usleep_range() for this fix, and the second patch
fixes the issue of DAMON by making it using the newly introduced function.


This patch (of 2):

Some kernel threads such as DAMON could need to repeatedly sleep in micro
seconds level.  Because usleep_range() sleeps in uninterruptible state,
however, such threads would make /proc/loadavg reports fake load.

To help such cases, this commit implements a variant of usleep_range()
called usleep_idle_range().  It is same to usleep_range() but sets the
state of the current task as TASK_IDLE while sleeping.

Link: https://lkml.kernel.org/r/20211126145015.15862-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20211126145015.15862-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/delay.h |   14 +++++++++++++-
 kernel/time/timer.c   |   16 +++++++++-------
 2 files changed, 22 insertions(+), 8 deletions(-)

--- a/include/linux/delay.h~timers-implement-usleep_idle_range
+++ a/include/linux/delay.h
@@ -20,6 +20,7 @@
  */
 
 #include <linux/math.h>
+#include <linux/sched.h>
 
 extern unsigned long loops_per_jiffy;
 
@@ -58,7 +59,18 @@ void calibrate_delay(void);
 void __attribute__((weak)) calibration_delay_done(void);
 void msleep(unsigned int msecs);
 unsigned long msleep_interruptible(unsigned int msecs);
-void usleep_range(unsigned long min, unsigned long max);
+void usleep_range_state(unsigned long min, unsigned long max,
+			unsigned int state);
+
+static inline void usleep_range(unsigned long min, unsigned long max)
+{
+	usleep_range_state(min, max, TASK_UNINTERRUPTIBLE);
+}
+
+static inline void usleep_idle_range(unsigned long min, unsigned long max)
+{
+	usleep_range_state(min, max, TASK_IDLE);
+}
 
 static inline void ssleep(unsigned int seconds)
 {
--- a/kernel/time/timer.c~timers-implement-usleep_idle_range
+++ a/kernel/time/timer.c
@@ -2054,26 +2054,28 @@ unsigned long msleep_interruptible(unsig
 EXPORT_SYMBOL(msleep_interruptible);
 
 /**
- * usleep_range - Sleep for an approximate time
- * @min: Minimum time in usecs to sleep
- * @max: Maximum time in usecs to sleep
+ * usleep_range_state - Sleep for an approximate time in a given state
+ * @min:	Minimum time in usecs to sleep
+ * @max:	Maximum time in usecs to sleep
+ * @state:	State of the current task that will be while sleeping
  *
  * In non-atomic context where the exact wakeup time is flexible, use
- * usleep_range() instead of udelay().  The sleep improves responsiveness
+ * usleep_range_state() instead of udelay().  The sleep improves responsiveness
  * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces
  * power usage by allowing hrtimers to take advantage of an already-
  * scheduled interrupt instead of scheduling a new one just for this sleep.
  */
-void __sched usleep_range(unsigned long min, unsigned long max)
+void __sched usleep_range_state(unsigned long min, unsigned long max,
+				unsigned int state)
 {
 	ktime_t exp = ktime_add_us(ktime_get(), min);
 	u64 delta = (u64)(max - min) * NSEC_PER_USEC;
 
 	for (;;) {
-		__set_current_state(TASK_UNINTERRUPTIBLE);
+		__set_current_state(state);
 		/* Do not return before the requested sleep time has elapsed */
 		if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS))
 			break;
 	}
 }
-EXPORT_SYMBOL(usleep_range);
+EXPORT_SYMBOL(usleep_range_state);
_

Patches currently in -mm which might be from sj@kernel.org are

timers-implement-usleep_idle_range.patch
mm-damon-core-fix-fake-load-reports-due-to-uninterruptible-sleeps.patch
mm-damon-remove-some-no-need-func-definitions-in-damonh-file-fix.patch

Re: + timers-implement-usleep_idle_range.patch added to -mm tree

[SeongJae Park]

Hello Andrew,

On Sat, 27 Nov 2021 15:56:53 -0800 akpm@linux-foundation.org wrote:

> 
> The patch titled
>      Subject: timers: implement usleep_idle_range()
> has been added to the -mm tree.  Its filename is
>      timers-implement-usleep_idle_range.patch
> 
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/timers-implement-usleep_idle_range.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/timers-implement-usleep_idle_range.patch
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: SeongJae Park <sj@kernel.org>
> Subject: timers: implement usleep_idle_range()
> 
> Patch series "mm/damon: Fix fake /proc/loadavg reports", v3.
> 
> This patchset fixes DAMON's fake load report issue.  The first patch makes
> yet another variant of usleep_range() for this fix, and the second patch
> fixes the issue of DAMON by making it using the newly introduced function.
> 
> 
> This patch (of 2):
> 
> Some kernel threads such as DAMON could need to repeatedly sleep in micro
> seconds level.  Because usleep_range() sleeps in uninterruptible state,
> however, such threads would make /proc/loadavg reports fake load.
> 
> To help such cases, this commit implements a variant of usleep_range()
> called usleep_idle_range().  It is same to usleep_range() but sets the
> state of the current task as TASK_IDLE while sleeping.
> 
> Link: https://lkml.kernel.org/r/20211126145015.15862-1-sj@kernel.org
> Link: https://lkml.kernel.org/r/20211126145015.15862-2-sj@kernel.org
> Signed-off-by: SeongJae Park <sj@kernel.org>
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: John Stultz <john.stultz@linaro.org>
> Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Thank you for picking this patch series.  Could you please also add
'Tested-by:' tags for Oleksandr[1]?

[1] https://lore.kernel.org/linux-mm/51190182.RbnaydPRjS@natalenko.name/


Thanks,
SJ

> ---
> 
>  include/linux/delay.h |   14 +++++++++++++-
>  kernel/time/timer.c   |   16 +++++++++-------
>  2 files changed, 22 insertions(+), 8 deletions(-)