* [PATCH v2] PM: Use 64-bit timekeeping
@ 2015-01-28 4:38 Tina Ruchandani
2015-01-28 7:42 ` Pavel Machek
0 siblings, 1 reply; 2+ messages in thread
From: Tina Ruchandani @ 2015-01-28 4:38 UTC (permalink / raw)
To: Linux PM List
Cc: Arnd Bergmann, Pavel Machek, Len Brown, Rafael J. Wysocki, linux-kernel
The freezer try_to_freeze_tasks uses 'struct timeval' for start
and end times, tracking time taken to freeze tasks. 'struct timeval'
on 32-bit systems will have its tv_sec overflow in year 2038 and
beyond. This patches uses 'ktime_t' (which has 64 bit values
for seconds) for start and end time.
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
---
Changes in v2:
- Use ktime_t to be able to use ktime_ms_delta
which is more efficient than timespec64 based methods.
---
kernel/power/process.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 5a6ec86..52414dd 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -17,6 +17,7 @@
#include <linux/delay.h>
#include <linux/workqueue.h>
#include <linux/kmod.h>
+#include <linux/ktime.h>
#include <trace/events/power.h>
/*
@@ -30,13 +31,12 @@ static int try_to_freeze_tasks(bool user_only)
unsigned long end_time;
unsigned int todo;
bool wq_busy = false;
- struct timeval start, end;
- u64 elapsed_msecs64;
+ ktime_t start, end;
unsigned int elapsed_msecs;
bool wakeup = false;
int sleep_usecs = USEC_PER_MSEC;
- do_gettimeofday(&start);
+ start = ktime_get();
end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
@@ -78,10 +78,8 @@ static int try_to_freeze_tasks(bool user_only)
sleep_usecs *= 2;
}
- do_gettimeofday(&end);
- elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
- do_div(elapsed_msecs64, NSEC_PER_MSEC);
- elapsed_msecs = elapsed_msecs64;
+ end = ktime_get();
+ elapsed_msecs = (unsigned int) ktime_ms_delta(end, start);
if (todo) {
printk("\n");
--
2.2.0.rc0.207.ga3a616c
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] PM: Use 64-bit timekeeping
2015-01-28 4:38 [PATCH v2] PM: Use 64-bit timekeeping Tina Ruchandani
@ 2015-01-28 7:42 ` Pavel Machek
0 siblings, 0 replies; 2+ messages in thread
From: Pavel Machek @ 2015-01-28 7:42 UTC (permalink / raw)
To: Tina Ruchandani
Cc: Linux PM List, Arnd Bergmann, Len Brown, Rafael J. Wysocki, linux-kernel
On Wed 2015-01-28 10:08:37, Tina Ruchandani wrote:
> The freezer try_to_freeze_tasks uses 'struct timeval' for start
> and end times, tracking time taken to freeze tasks. 'struct timeval'
> on 32-bit systems will have its tv_sec overflow in year 2038 and
> beyond. This patches uses 'ktime_t' (which has 64 bit values
> for seconds) for start and end time.
>
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Nicer code, and without the overflow. Thanks!
Acked-by: Pavel Machek <pavel@ucw.cz>
> ---
> Changes in v2:
> - Use ktime_t to be able to use ktime_ms_delta
> which is more efficient than timespec64 based methods.
> ---
> kernel/power/process.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index 5a6ec86..52414dd 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -17,6 +17,7 @@
> #include <linux/delay.h>
> #include <linux/workqueue.h>
> #include <linux/kmod.h>
> +#include <linux/ktime.h>
> #include <trace/events/power.h>
x>
> /*
> @@ -30,13 +31,12 @@ static int try_to_freeze_tasks(bool user_only)
> unsigned long end_time;
> unsigned int todo;
> bool wq_busy = false;
> - struct timeval start, end;
> - u64 elapsed_msecs64;
> + ktime_t start, end;
> unsigned int elapsed_msecs;
> bool wakeup = false;
> int sleep_usecs = USEC_PER_MSEC;
>
> - do_gettimeofday(&start);
> + start = ktime_get();
>
> end_time = jiffies + msecs_to_jiffies(freeze_timeout_msecs);
>
> @@ -78,10 +78,8 @@ static int try_to_freeze_tasks(bool user_only)
> sleep_usecs *= 2;
> }
>
> - do_gettimeofday(&end);
> - elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
> - do_div(elapsed_msecs64, NSEC_PER_MSEC);
> - elapsed_msecs = elapsed_msecs64;
> + end = ktime_get();
> + elapsed_msecs = (unsigned int) ktime_ms_delta(end, start);
>
> if (todo) {
> printk("\n");
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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2015-01-28 7:42 ` Pavel Machek
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