diff options
Diffstat (limited to 'arch/x86/kernel/tsc.c')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 29 |
1 files changed, 14 insertions, 15 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index aab0c82e0a0d..15b5e98a86f9 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -185,8 +185,7 @@ static void __init cyc2ns_init_boot_cpu(void) /* * Secondary CPUs do not run through tsc_init(), so set up * all the scale factors for all CPUs, assuming the same - * speed as the bootup CPU. (cpufreq notifiers will fix this - * up if their speed diverges) + * speed as the bootup CPU. */ static void __init cyc2ns_init_secondary_cpus(void) { @@ -940,12 +939,12 @@ void tsc_restore_sched_clock_state(void) } #ifdef CONFIG_CPU_FREQ -/* Frequency scaling support. Adjust the TSC based timer when the cpu frequency +/* + * Frequency scaling support. Adjust the TSC based timer when the CPU frequency * changes. * - * RED-PEN: On SMP we assume all CPUs run with the same frequency. It's - * not that important because current Opteron setups do not support - * scaling on SMP anyroads. + * NOTE: On SMP the situation is not fixable in general, so simply mark the TSC + * as unstable and give up in those cases. * * Should fix up last_tsc too. Currently gettimeofday in the * first tick after the change will be slightly wrong. @@ -959,22 +958,22 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data) { struct cpufreq_freqs *freq = data; - unsigned long *lpj; - lpj = &boot_cpu_data.loops_per_jiffy; -#ifdef CONFIG_SMP - if (!(freq->flags & CPUFREQ_CONST_LOOPS)) - lpj = &cpu_data(freq->cpu).loops_per_jiffy; -#endif + if (num_online_cpus() > 1) { + mark_tsc_unstable("cpufreq changes on SMP"); + return 0; + } if (!ref_freq) { ref_freq = freq->old; - loops_per_jiffy_ref = *lpj; + loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy; tsc_khz_ref = tsc_khz; } + if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || - (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { - *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); + (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { + boot_cpu_data.loops_per_jiffy = + cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new); tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new); if (!(freq->flags & CPUFREQ_CONST_LOOPS)) |