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cputime: Optimize jiffies_to_cputime(1)

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For powerpc with CONFIG_VIRT_CPU_ACCOUNTING
jiffies_to_cputime(1) is not compile time constant and run time
calculations are quite expensive. To optimize we use
precomputed value. For all other architectures is is
preprocessor definition.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
LKML-Reference: <1248862529-6063-5-git-send-email-sgruszka@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Stanislaw Gruszka
2009-07-29 12:15:29 +02:00
committed by Ingo Molnar
parent d1e3b6d195
commit a42548a188
8 changed files with 29 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/powerpc/include/asm/cputime.h
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@@ -18,6 +18,9 @@
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
#include <asm-generic/cputime.h>
#ifdef __KERNEL__
static inline void setup_cputime_one_jiffy(void) { }
#endif
#else
#include <linux/types.h>
@@ -48,6 +51,11 @@ typedef u64 cputime64_t;
#ifdef __KERNEL__
/*
* One jiffy in timebase units computed during initialization
*/
extern cputime_t cputime_one_jiffy;
/*
* Convert cputime <-> jiffies
*/
@@ -89,6 +97,11 @@ static inline cputime_t jiffies_to_cputime(const unsigned long jif)
return ct;
}
static inline void setup_cputime_one_jiffy(void)
{
cputime_one_jiffy = jiffies_to_cputime(1);
}
static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
{
cputime_t ct;