taskstats scaled time cleanup

This moves the ability to scale cputime into generic code.  This allows us
to fix the issue in kernel/timer.c (noticed by Balbir) where we could only
add an unscaled value to the scaled utime/stime.

This adds a cputime_to_scaled function.  As before, the POWERPC version
does the scaling based on the last SPURR/PURR ratio calculated.  The
generic and s390 (only other arch to implement asm/cputime.h) versions are
both NOPs.

Also moves the SPURR and PURR snapshots closer.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/asm-powerpc/cputime.h b/include/asm-powerpc/cputime.h
index 310804485208..f42e623030ee 100644
--- a/include/asm-powerpc/cputime.h
+++ b/include/asm-powerpc/cputime.h
@@ -52,12 +52,26 @@ typedef u64 cputime64_t;
  * Convert cputime <-> jiffies
  */
 extern u64 __cputime_jiffies_factor;
+DECLARE_PER_CPU(unsigned long, cputime_last_delta);
+DECLARE_PER_CPU(unsigned long, cputime_scaled_last_delta);
 
 static inline unsigned long cputime_to_jiffies(const cputime_t ct)
 {
 	return mulhdu(ct, __cputime_jiffies_factor);
 }
 
+/* Estimate the scaled cputime by scaling the real cputime based on
+ * the last scaled to real ratio */
+static inline cputime_t cputime_to_scaled(const cputime_t ct)
+{
+	if (cpu_has_feature(CPU_FTR_SPURR) &&
+	    per_cpu(cputime_last_delta, smp_processor_id()))
+		return ct *
+			per_cpu(cputime_scaled_last_delta, smp_processor_id())/
+			per_cpu(cputime_last_delta, smp_processor_id());
+	return ct;
+}
+
 static inline cputime_t jiffies_to_cputime(const unsigned long jif)
 {
 	cputime_t ct;