diff options
Diffstat (limited to 'sys/arch/i386/isa/clock.c')
| -rw-r--r-- | sys/arch/i386/isa/clock.c | 35 |
1 files changed, 29 insertions, 6 deletions
diff --git a/sys/arch/i386/isa/clock.c b/sys/arch/i386/isa/clock.c index c9ac92eb481..8e674950b6d 100644 --- a/sys/arch/i386/isa/clock.c +++ b/sys/arch/i386/isa/clock.c @@ -1,4 +1,4 @@ -/* $OpenBSD: clock.c,v 1.46 2011/07/05 17:11:07 oga Exp $ */ +/* $OpenBSD: clock.c,v 1.47 2012/11/10 09:45:05 mglocker Exp $ */ /* $NetBSD: clock.c,v 1.39 1996/05/12 23:11:54 mycroft Exp $ */ /*- @@ -376,11 +376,34 @@ i8254_delay(int n) void calibrate_cyclecounter(void) { - unsigned long long count, last_count; - - __asm __volatile("rdtsc" : "=A" (last_count)); - delay(1000000); - __asm __volatile("rdtsc" : "=A" (count)); + struct cpu_info *ci; + unsigned long long count, last_count, msr; + + ci = curcpu(); + + if ((ci->ci_flags & CPUF_CONST_TSC) && + (cpu_perf_eax & CPUIDEAX_VERID) > 1 && + CPUIDEDX_NUM_FC(cpu_perf_edx) > 1) { + msr = rdmsr(MSR_PERF_FIXED_CTR_CTRL) | MSR_PERF_FIXED_CTR1_EN; + wrmsr(MSR_PERF_FIXED_CTR_CTRL, msr); + msr = rdmsr(MSR_PERF_GLOBAL_CTRL) | MSR_PERF_GLOBAL_CTR1_EN; + wrmsr(MSR_PERF_GLOBAL_CTRL, msr); + + last_count = rdmsr(MSR_PERF_FIXED_CTR1); + delay(1000000); + count = rdmsr(MSR_PERF_FIXED_CTR1); + + msr = rdmsr(MSR_PERF_FIXED_CTR_CTRL); + msr &= ~MSR_PERF_FIXED_CTR1_EN; + wrmsr(MSR_PERF_FIXED_CTR_CTRL, msr); + msr = rdmsr(MSR_PERF_GLOBAL_CTRL); + msr &= ~MSR_PERF_GLOBAL_CTR1_EN; + wrmsr(MSR_PERF_GLOBAL_CTRL, msr); + } else { + __asm __volatile("rdtsc" : "=A" (last_count)); + delay(1000000); + __asm __volatile("rdtsc" : "=A" (count)); + } cpuspeed = ((count - last_count) + 999999) / 1000000; } |