Frederic Weisbecker <fweis...@gmail.com> writes:
> The full dynticks cputime accounting that we'll soon introduce
> will rely on sched_clock(). And its clock can have a per
> nanosecond granularity.
>
> To prepare for this, we need to have a cputime_t implementation
> that has this precision.
>
> ia64 virtual cputime accounting already uses that granularity
> so all we need is to librarize its implementation in the asm
> generic headers.
...except that for it to be truly generic (i.e. usable on 32-bit arches),
it should be using do_div() for 64-bit divides.
I understand this series is targetted at 64-bit platforms currently, but
I'm looking (again) at getting adaptive NOHZ working on ARM, and this
was the first obvious obstacle to even compiling.
I see this is already merged into tip/sched/core, so below is a patch on
top of that to convert to using do_div(). If you're OK with the
approach, I'll post it formally to LKML.
Thanks,
Kevin
>From b1572b5ae67d4221277484e59d571b639775af70 Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khil...@linaro.org>
Date: Thu, 14 Feb 2013 11:27:36 -0800
Subject: [PATCH] cputime: use do_div() for nsec resolution conversion helpers
For the nsec resolution conversions to be useful on non 64-bit
architectures, do_div() needs to be used for the 64-bit divisions.
Cc: Frederic Weisbecker <fweis...@gmail.com>
Signed-off-by: Kevin Hilman <khil...@linaro.org>
---
include/asm-generic/cputime_nsecs.h | 51 +++++++++++++++++++++++++++----------
1 file changed, 37 insertions(+), 14 deletions(-)
diff --git a/include/asm-generic/cputime_nsecs.h
b/include/asm-generic/cputime_nsecs.h
index b6485ca..daa6075 100644
--- a/include/asm-generic/cputime_nsecs.h
+++ b/include/asm-generic/cputime_nsecs.h
@@ -24,13 +24,17 @@ typedef u64 __nocast cputime64_t;
/*
* Convert cputime <-> jiffies (HZ)
*/
-#define cputime_to_jiffies(__ct) \
- ((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+static inline u64 cputime_to_jiffies(const cputime_t ct)
+{
+ cputime_t __ct = ct;
+
+ do_div(__ct, NSEC_PER_SEC / HZ);
+ return __ct;
+}
#define cputime_to_scaled(__ct) (__ct)
#define jiffies_to_cputime(__jif) \
(__force cputime_t)((__jif) * (NSEC_PER_SEC / HZ))
-#define cputime64_to_jiffies64(__ct) \
- ((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+#define cputime64_to_jiffies64(__ct) cputime_to_jiffies(__ct)
#define jiffies64_to_cputime64(__jif) \
(__force cputime64_t)((__jif) * (NSEC_PER_SEC / HZ))
@@ -44,8 +48,13 @@ typedef u64 __nocast cputime64_t;
/*
* Convert cputime <-> microseconds
*/
-#define cputime_to_usecs(__ct) \
- ((__force u64)(__ct) / NSEC_PER_USEC)
+static inline u64 cputime_to_usecs(const cputime_t ct)
+{
+ cputime_t __ct = ct;
+
+ do_div(__ct, NSEC_PER_USEC);
+ return __ct;
+}
#define usecs_to_cputime(__usecs) \
(__force cputime_t)((__usecs) * NSEC_PER_USEC)
#define usecs_to_cputime64(__usecs) \
@@ -54,8 +63,13 @@ typedef u64 __nocast cputime64_t;
/*
* Convert cputime <-> seconds
*/
-#define cputime_to_secs(__ct) \
- ((__force u64)(__ct) / NSEC_PER_SEC)
+static inline u64 cputime_to_secs(const cputime_t ct)
+{
+ cputime_t __ct = ct;
+
+ do_div(__ct, NSEC_PER_SEC);
+ return __ct;
+}
#define secs_to_cputime(__secs) \
(__force cputime_t)((__secs) * NSEC_PER_SEC)
@@ -69,8 +83,10 @@ static inline cputime_t timespec_to_cputime(const struct
timespec *val)
}
static inline void cputime_to_timespec(const cputime_t ct, struct timespec
*val)
{
- val->tv_sec = (__force u64) ct / NSEC_PER_SEC;
- val->tv_nsec = (__force u64) ct % NSEC_PER_SEC;
+ cputime_t __ct = ct;
+
+ val->tv_nsec = do_div(__ct, NSEC_PER_SEC);
+ val->tv_sec = __ct;
}
/*
@@ -83,15 +99,22 @@ static inline cputime_t timeval_to_cputime(struct timeval
*val)
}
static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
{
- val->tv_sec = (__force u64) ct / NSEC_PER_SEC;
- val->tv_usec = ((__force u64) ct % NSEC_PER_SEC) / NSEC_PER_USEC;
+ cputime_t __ct = ct;
+
+ val->tv_usec = do_div(__ct, NSEC_PER_SEC) / NSEC_PER_USEC;
+ val->tv_sec = __ct;
}
/*
* Convert cputime <-> clock (USER_HZ)
*/
-#define cputime_to_clock_t(__ct) \
- ((__force u64)(__ct) / (NSEC_PER_SEC / USER_HZ))
+static inline u64 cputime_to_clock_t(const cputime_t ct)
+{
+ cputime_t __ct = ct;
+
+ do_div(__ct, (NSEC_PER_SEC / USER_HZ));
+ return __ct;
+}
#define clock_t_to_cputime(__x) \
(__force cputime_t)((__x) * (NSEC_PER_SEC / USER_HZ))
--
1.8.1.2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
