From c29601e9c1e7893d1755364e350c9188bd56d69f Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sat, 16 Apr 2005 15:25:05 -0700 Subject: [PATCH] x86_64: Support constantly ticking TSCs On Intel Noconas the TSC ticks with a constant frequency. Don't scale the factor used by udelay when cpufreq changes the frequency. This generalizes an earlier patch by Intel for this. Cc: Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/time.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'arch/x86_64/kernel/time.c') diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 3bafe438fa7..c7a1b50b4af 100644 --- a/arch/x86_64/kernel/time.c +++ b/arch/x86_64/kernel/time.c @@ -614,6 +614,9 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, struct cpufreq_freqs *freq = data; unsigned long *lpj, dummy; + if (cpu_has(&cpu_data[freq->cpu], X86_FEATURE_CONSTANT_TSC)) + return 0; + lpj = &dummy; if (!(freq->flags & CPUFREQ_CONST_LOOPS)) #ifdef CONFIG_SMP @@ -622,8 +625,6 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, lpj = &boot_cpu_data.loops_per_jiffy; #endif - - if (!ref_freq) { ref_freq = freq->old; loops_per_jiffy_ref = *lpj; -- cgit v1.2.3