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SubjectRe: [PATCH] timer: Added usleep[_range] timer
On Mon, 19 Jul 2010 15:12:34 -0700
Patrick Pannuto <ppannuto@codeaurora.org> wrote:

> Respun without interruptible...
>

And without all the nice changelog info. Oh well.

> usleep[_range] are finer precision implementations of msleep
> and are designed to be drop-in replacements for udelay where
> a precise sleep / busy-wait is unnecessary. They also allow
> an easy interface to specify slack when a precise (ish)
> wakeup is unnecessary to help minimize wakeups
>
> Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
> ---
> include/linux/delay.h | 6 ++++++
> kernel/timer.c | 22 ++++++++++++++++++++++
> 2 files changed, 28 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/delay.h b/include/linux/delay.h
> index fd832c6..0e303d1 100644
> --- a/include/linux/delay.h
> +++ b/include/linux/delay.h
> @@ -45,6 +45,12 @@ extern unsigned long lpj_fine;
> void calibrate_delay(void);
> void msleep(unsigned int msecs);
> unsigned long msleep_interruptible(unsigned int msecs);
> +void usleep_range(unsigned long min, unsigned long max);
> +
> +static inline void usleep(unsigned long usecs)
> +{
> + usleep_range(usecs, usecs);
> +}
>
> static inline void ssleep(unsigned int seconds)
> {
> diff --git a/kernel/timer.c b/kernel/timer.c
> index ee305c8..4e6746f 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -1750,3 +1750,25 @@ unsigned long msleep_interruptible(unsigned int msecs)
> }
>
> EXPORT_SYMBOL(msleep_interruptible);
> +
> +static int __sched do_usleep_range(unsigned long min, unsigned long max)
> +{
> + ktime_t kmin;
> + unsigned long delta;
> +
> + kmin = ktime_set(0, min * NSEC_PER_USEC);
> + delta = max - min;
> + return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
> +}
> +
> +/**
> + * usleep_range - Drop in replacement for udelay where wakeup is flexible
> + * @min: Minimum time in usecs to sleep
> + * @max: Maximum time in usecs to sleep
> + */
> +void usleep_range(unsigned long min, unsigned long max)
> +{
> + __set_current_state(TASK_UNINTERRUPTIBLE);
> + do_usleep_range(min, max);
> +}
> +EXPORT_SYMBOL(usleep_range);

Fair enough, I guess. People can go over and look at the
schedule_hrtimeout_range() documentation to work out why on earth they
should specify a "range".

Of course, nobody will actually think to _use_ this thing. Someone
owes me a "usleep_range is preferred over usleep" checkpatch rule!



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