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authorStanislaw Gruszka <sgruszka@redhat.com>2009-07-29 12:15:29 +0200
committerIngo Molnar <mingo@elte.hu>2009-08-03 14:48:36 +0200
commita42548a18866e87092db93b771e6c5b060d78401 (patch)
tree897acf5794920ec9c6fd7f87af63908d0c1988f9 /arch/powerpc/kernel/time.c
parentd1e3b6d195770bd422e3229b88edfc154b6a27dd (diff)
cputime: Optimize jiffies_to_cputime(1)
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>
Diffstat (limited to 'arch/powerpc/kernel/time.c')
-rw-r--r--arch/powerpc/kernel/time.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index eae4511ceea..211d7b0cd37 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -193,6 +193,8 @@ EXPORT_SYMBOL(__cputime_clockt_factor);
DEFINE_PER_CPU(unsigned long, cputime_last_delta);
DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
+cputime_t cputime_one_jiffy;
+
static void calc_cputime_factors(void)
{
struct div_result res;
@@ -500,6 +502,7 @@ static int __init iSeries_tb_recal(void)
tb_to_xs = divres.result_low;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
vdso_data->tb_to_xs = tb_to_xs;
+ setup_cputime_one_jiffy();
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
@@ -945,6 +948,7 @@ void __init time_init(void)
tb_ticks_per_usec = ppc_tb_freq / 1000000;
tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
calc_cputime_factors();
+ setup_cputime_one_jiffy();
/*
* Calculate the length of each tick in ns. It will not be