X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fi386%2Fkernel%2Ftimers%2Ftimer_tsc.c;h=f1187ddb0d0fc07809a3f5f20ab43177b6fbe61f;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=180444d87824e4299979a68b8f726da94ec50725;hpb=cee37fe97739d85991964371c1f3a745c00dd236;p=linux-2.6.git diff --git a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c index 180444d87..f1187ddb0 100644 --- a/arch/i386/kernel/timers/timer_tsc.c +++ b/arch/i386/kernel/timers/timer_tsc.c @@ -24,6 +24,7 @@ #include "mach_timer.h" #include +#include #ifdef CONFIG_HPET_TIMER static unsigned long hpet_usec_quotient; @@ -33,9 +34,7 @@ static struct timer_opts timer_tsc; static inline void cpufreq_delayed_get(void); -int tsc_disable __initdata = 0; - -extern spinlock_t i8253_lock; +int tsc_disable __devinitdata = 0; static int use_tsc; /* Number of usecs that the last interrupt was delayed */ @@ -46,27 +45,41 @@ static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */ static unsigned long long monotonic_base; static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED; +/* Avoid compensating for lost ticks before TSCs are synched */ +static int detect_lost_ticks; +static int __init start_lost_tick_compensation(void) +{ + detect_lost_ticks = 1; + return 0; +} +late_initcall(start_lost_tick_compensation); + /* convert from cycles(64bits) => nanoseconds (64bits) * basic equation: * ns = cycles / (freq / ns_per_sec) * ns = cycles * (ns_per_sec / freq) - * ns = cycles * (10^9 / (cpu_mhz * 10^6)) - * ns = cycles * (10^3 / cpu_mhz) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) * * Then we use scaling math (suggested by george@mvista.com) to get: - * ns = cycles * (10^3 * SC / cpu_mhz) / SC + * ns = cycles * (10^6 * SC / cpu_khz) / SC * ns = cycles * cyc2ns_scale / SC * * And since SC is a constant power of two, we can convert the div - * into a shift. + * into a shift. + * + * We can use khz divisor instead of mhz to keep a better percision, since + * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. + * (mathieu.desnoyers@polymtl.ca) + * * -johnstul@us.ibm.com "math is hard, lets go shopping!" */ -static unsigned long cyc2ns_scale; +static unsigned long cyc2ns_scale __read_mostly; #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ -static inline void set_cyc2ns_scale(unsigned long cpu_mhz) +static inline void set_cyc2ns_scale(unsigned long cpu_khz) { - cyc2ns_scale = (1000 << CYC2NS_SCALE_FACTOR)/cpu_mhz; + cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz; } static inline unsigned long long cycles_2_ns(unsigned long long cyc) @@ -192,7 +205,8 @@ static void mark_offset_tsc_hpet(void) /* lost tick compensation */ offset = hpet_readl(HPET_T0_CMP) - hpet_tick; - if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) { + if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0)) + && detect_lost_ticks) { int lost_ticks = (offset - hpet_last) / hpet_tick; jiffies_64 += lost_ticks; } @@ -256,7 +270,7 @@ static unsigned long loops_per_jiffy_ref = 0; #ifndef CONFIG_SMP static unsigned long fast_gettimeoffset_ref = 0; -static unsigned long cpu_khz_ref = 0; +static unsigned int cpu_khz_ref = 0; #endif static int @@ -265,9 +279,13 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, { struct cpufreq_freqs *freq = data; - if (val != CPUFREQ_RESUMECHANGE) + if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE) write_seqlock_irq(&xtime_lock); if (!ref_freq) { + if (!freq->old){ + ref_freq = freq->new; + goto end; + } ref_freq = freq->old; loops_per_jiffy_ref = cpu_data[freq->cpu].loops_per_jiffy; #ifndef CONFIG_SMP @@ -287,13 +305,14 @@ time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, if (use_tsc) { if (!(freq->flags & CPUFREQ_CONST_LOOPS)) { fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_ref, freq->new, ref_freq); - set_cyc2ns_scale(cpu_khz/1000); + set_cyc2ns_scale(cpu_khz); } } #endif } - if (val != CPUFREQ_RESUMECHANGE) +end: + if (val != CPUFREQ_RESUMECHANGE && val != CPUFREQ_SUSPENDCHANGE) write_sequnlock_irq(&xtime_lock); return 0; @@ -323,10 +342,12 @@ static inline void cpufreq_delayed_get(void) { return; } int recalibrate_cpu_khz(void) { #ifndef CONFIG_SMP - unsigned long cpu_khz_old = cpu_khz; + unsigned int cpu_khz_old = cpu_khz; if (cpu_has_tsc) { + local_irq_disable(); init_cpu_khz(); + local_irq_enable(); cpu_data[0].loops_per_jiffy = cpufreq_scale(cpu_data[0].loops_per_jiffy, cpu_khz_old, @@ -415,7 +436,7 @@ static void mark_offset_tsc(void) delta += delay_at_last_interrupt; lost = delta/(1000000/HZ); delay = delta%(1000000/HZ); - if (lost >= 2) { + if (lost >= 2 && detect_lost_ticks) { jiffies_64 += lost-1; /* sanity check to ensure we're not always losing ticks */ @@ -534,15 +555,29 @@ static int __init init_tsc(char* override) :"=a" (cpu_khz), "=d" (edx) :"r" (tsc_quotient), "0" (eax), "1" (edx)); - printk("Detected %lu.%03lu MHz processor.\n", cpu_khz / 1000, cpu_khz % 1000); + printk("Detected %u.%03u MHz processor.\n", + cpu_khz / 1000, cpu_khz % 1000); } - set_cyc2ns_scale(cpu_khz/1000); + set_cyc2ns_scale(cpu_khz); return 0; } } return -ENODEV; } +static int tsc_resume(void) +{ + write_seqlock(&monotonic_lock); + /* Assume this is the last mark offset time */ + rdtsc(last_tsc_low, last_tsc_high); +#ifdef CONFIG_HPET_TIMER + if (is_hpet_enabled() && hpet_use_timer) + hpet_last = hpet_readl(HPET_COUNTER); +#endif + write_sequnlock(&monotonic_lock); + return 0; +} + #ifndef CONFIG_X86_TSC /* disable flag for tsc. Takes effect by clearing the TSC cpu flag * in cpu/common.c */ @@ -572,6 +607,8 @@ static struct timer_opts timer_tsc = { .get_offset = get_offset_tsc, .monotonic_clock = monotonic_clock_tsc, .delay = delay_tsc, + .read_timer = read_timer_tsc, + .resume = tsc_resume, }; struct init_timer_opts __initdata timer_tsc_init = {