diff options
| author | Andi Kleen <ak@suse.de> | 2005-04-16 15:25:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:25:05 -0700 |
| commit | c29601e9c1e7893d1755364e350c9188bd56d69f (patch) | |
| tree | 14813ddce4d8897b40cc8b3a2f76ace3ac58b36f /arch | |
| parent | dc37db4d8cb376bb67c6357c50d707ced3d71c39 (diff) | |
| download | lwn-c29601e9c1e7893d1755364e350c9188bd56d69f.tar.gz lwn-c29601e9c1e7893d1755364e350c9188bd56d69f.zip | |
[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: <venkatesh.pallipadi@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86_64/kernel/setup.c | 5 | ||||
| -rw-r--r-- | arch/x86_64/kernel/time.c | 5 |
2 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index a191d4831789..b06221e31952 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -855,6 +855,8 @@ static void __init init_intel(struct cpuinfo_x86 *c) if (c->x86 == 15) c->x86_cache_alignment = c->x86_clflush_size * 2; + if (c->x86 >= 15) + set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability); } void __init get_cpu_vendor(struct cpuinfo_x86 *c) @@ -1055,7 +1057,8 @@ static int show_cpuinfo(struct seq_file *m, void *v) NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, /* Other (Linux-defined) */ - "cxmmx", "k6_mtrr", "cyrix_arr", "centaur_mcr", NULL, NULL, NULL, NULL, + "cxmmx", NULL, "cyrix_arr", "centaur_mcr", "k8c+", + "constant_tsc", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c index 3bafe438fa75..c7a1b50b4af3 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; |