From: Kevin Hilman <khilman@linaro.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Li Zhong <zhong@linux.vnet.ibm.com>,
Namhyung Kim <namhyung.kim@lge.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Nicolas Pitre <nicolas.pitre@linaro.org>
Subject: Re: [PATCH 2/8] cputime: Librarize per nsecs resolution cputime definitions
Date: Thu, 14 Feb 2013 11:49:28 -0800 [thread overview]
Message-ID: <87ehgid6bb.fsf@linaro.org> (raw)
In-Reply-To: <1359399845-10568-3-git-send-email-fweisbec@gmail.com> (Frederic Weisbecker's message of "Mon, 28 Jan 2013 20:03:59 +0100")
Frederic Weisbecker <fweisbec@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 <khilman@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 <fweisbec@gmail.com>
Signed-off-by: Kevin Hilman <khilman@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
next prev parent reply other threads:[~2013-02-14 19:49 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-28 19:03 [GIT PULL] cputime: Full dynticks task/cputime accounting v7 Frederic Weisbecker
2013-01-28 19:03 ` [PATCH 1/8] context_tracking: Export context state for generic vtime Frederic Weisbecker
2013-01-28 19:03 ` [PATCH 2/8] cputime: Librarize per nsecs resolution cputime definitions Frederic Weisbecker
2013-02-14 19:49 ` Kevin Hilman [this message]
2013-02-20 16:07 ` Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 3/8] cputime: Move default nsecs_to_cputime() to jiffies based cputime file Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 4/8] cputime: Generic on-demand virtual cputime accounting Frederic Weisbecker
2013-02-08 3:07 ` Stephen Rothwell
2013-02-08 3:14 ` Stephen Rothwell
2013-02-08 3:19 ` [PATCH] cputime: restore CPU_ACCOUNTING config defaults for PPC64 Stephen Rothwell
2013-02-08 15:18 ` [tip:sched/core] cputime: Restore " tip-bot for Stephen Rothwell
2013-02-08 14:31 ` [PATCH 4/8] cputime: Generic on-demand virtual cputime accounting Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 5/8] cputime: Allow dynamic switch between tick/virtual based " Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 6/8] cputime: Use accessors to read task cputime stats Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 7/8] kvm: Prepare to add generic guest entry/exit callbacks Frederic Weisbecker
2013-01-28 19:04 ` [PATCH 8/8] cputime: Safely read cputime of full dynticks CPUs Frederic Weisbecker
2013-01-28 21:51 ` Sedat Dilek
2013-01-30 21:57 ` Sedat Dilek
2013-01-31 0:38 ` Frederic Weisbecker
2013-01-31 7:24 ` Sedat Dilek
2013-01-31 10:12 ` Frederic Weisbecker
2013-01-31 10:30 ` Sedat Dilek
2013-01-31 16:29 ` Frederic Weisbecker
2013-01-28 19:18 ` [GIT PULL] cputime: Full dynticks task/cputime accounting v7 Christoph Lameter
2013-01-28 19:21 ` Frederic Weisbecker
2013-01-28 20:14 ` Christoph Lameter
2013-01-29 1:42 ` Frederic Weisbecker
2013-01-29 0:02 ` Steven Rostedt
2013-01-29 1:36 ` Frederic Weisbecker
2013-01-29 2:36 ` Steven Rostedt
2013-01-29 2:39 ` Frederic Weisbecker
2013-01-29 2:44 ` Steven Rostedt
2013-01-29 3:29 ` Frederic Weisbecker
2013-01-29 4:38 ` Steven Rostedt
2013-01-29 15:12 ` Frederic Weisbecker
2013-01-29 16:46 ` Steven Rostedt
2013-01-29 16:55 ` Frederic Weisbecker
2013-01-29 17:08 ` Steven Rostedt
2013-01-29 21:26 ` Steven Rostedt
2013-01-29 21:37 ` Frederic Weisbecker
2013-02-15 1:55 ` Kevin Hilman
2013-02-15 14:04 ` Mats Liljegren
2013-02-15 15:06 ` Kevin Hilman
2013-02-20 15:53 ` Frederic Weisbecker
2013-02-20 17:53 ` Kevin Hilman
2013-02-20 15:44 ` Frederic Weisbecker
2013-02-20 18:48 ` Kevin Hilman
-- strict thread matches above, loose matches on Subject: below --
2013-01-23 0:03 [PATCH 0/8] cputime: Full dynticks task/cputime accounting v6 Frederic Weisbecker
2013-01-23 0:03 ` [PATCH 2/8] cputime: Librarize per nsecs resolution cputime definitions Frederic Weisbecker
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