taskstats: use real microsecond granularity for CPU times

The taskstats interface uses microsecond granularity for the user and
system time values.  The conversion from cputime to the taskstats values
uses the cputime_to_msecs primitive which effectively limits the
granularity to milliseconds.  Add the cputime_to_usecs primitive for
architectures that have better, more precise CPU time values.  Remove
cputime_to_msecs primitive because there are no more users left.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Luck Tony <tony.luck@intel.com>
Cc: Shailabh Nagar <nagar1234@in.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Shailabh Nagar <nagar@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 6 deletions

diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 8bdc6a9e577..1cf20bdfbec 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -124,23 +124,23 @@ static inline u64 cputime64_to_jiffies64(const cputime_t ct)
 }
 
 /*
- * Convert cputime <-> milliseconds
+ * Convert cputime <-> microseconds
  */
 extern u64 __cputime_msec_factor;
 
-static inline unsigned long cputime_to_msecs(const cputime_t ct)
+static inline unsigned long cputime_to_usecs(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_msec_factor);
+	return mulhdu(ct, __cputime_msec_factor) * USEC_PER_MSEC;
 }
 
-static inline cputime_t msecs_to_cputime(const unsigned long ms)
+static inline cputime_t usecs_to_cputime(const unsigned long us)
 {
 	cputime_t ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
-	ct = ms % 1000;
-	sec = ms / 1000;
+	ct = us % 1000000;
+	sec = us / 1000000;
 	if (ct) {
 		ct *= tb_ticks_per_sec;
 		do_div(ct, 1000);