diff options
Diffstat (limited to 'arch/i386/kernel/smpboot.c')
| -rw-r--r-- | arch/i386/kernel/smpboot.c | 178 |
1 files changed, 12 insertions, 166 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index f46a4d095e6..6ddffe8aabb 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -94,12 +94,6 @@ cpumask_t cpu_possible_map; EXPORT_SYMBOL(cpu_possible_map); static cpumask_t smp_commenced_mask; -/* TSC's upper 32 bits can't be written in eariler CPU (before prescott), there - * is no way to resync one AP against BP. TBD: for prescott and above, we - * should use IA64's algorithm - */ -static int __devinitdata tsc_sync_disabled; - /* Per CPU bogomips and other parameters */ struct cpuinfo_x86 cpu_data[NR_CPUS] __cacheline_aligned; EXPORT_SYMBOL(cpu_data); @@ -216,151 +210,6 @@ valid_k7: ; } -/* - * TSC synchronization. - * - * We first check whether all CPUs have their TSC's synchronized, - * then we print a warning if not, and always resync. - */ - -static struct { - atomic_t start_flag; - atomic_t count_start; - atomic_t count_stop; - unsigned long long values[NR_CPUS]; -} tsc __cpuinitdata = { - .start_flag = ATOMIC_INIT(0), - .count_start = ATOMIC_INIT(0), - .count_stop = ATOMIC_INIT(0), -}; - -#define NR_LOOPS 5 - -static void __init synchronize_tsc_bp(void) -{ - int i; - unsigned long long t0; - unsigned long long sum, avg; - long long delta; - unsigned int one_usec; - int buggy = 0; - - printk(KERN_INFO "checking TSC synchronization across %u CPUs: ", num_booting_cpus()); - - /* convert from kcyc/sec to cyc/usec */ - one_usec = cpu_khz / 1000; - - atomic_set(&tsc.start_flag, 1); - wmb(); - - /* - * We loop a few times to get a primed instruction cache, - * then the last pass is more or less synchronized and - * the BP and APs set their cycle counters to zero all at - * once. This reduces the chance of having random offsets - * between the processors, and guarantees that the maximum - * delay between the cycle counters is never bigger than - * the latency of information-passing (cachelines) between - * two CPUs. - */ - for (i = 0; i < NR_LOOPS; i++) { - /* - * all APs synchronize but they loop on '== num_cpus' - */ - while (atomic_read(&tsc.count_start) != num_booting_cpus()-1) - cpu_relax(); - atomic_set(&tsc.count_stop, 0); - wmb(); - /* - * this lets the APs save their current TSC: - */ - atomic_inc(&tsc.count_start); - - rdtscll(tsc.values[smp_processor_id()]); - /* - * We clear the TSC in the last loop: - */ - if (i == NR_LOOPS-1) - write_tsc(0, 0); - - /* - * Wait for all APs to leave the synchronization point: - */ - while (atomic_read(&tsc.count_stop) != num_booting_cpus()-1) - cpu_relax(); - atomic_set(&tsc.count_start, 0); - wmb(); - atomic_inc(&tsc.count_stop); - } - - sum = 0; - for (i = 0; i < NR_CPUS; i++) { - if (cpu_isset(i, cpu_callout_map)) { - t0 = tsc.values[i]; - sum += t0; - } - } - avg = sum; - do_div(avg, num_booting_cpus()); - - for (i = 0; i < NR_CPUS; i++) { - if (!cpu_isset(i, cpu_callout_map)) - continue; - delta = tsc.values[i] - avg; - if (delta < 0) - delta = -delta; - /* - * We report bigger than 2 microseconds clock differences. - */ - if (delta > 2*one_usec) { - long long realdelta; - - if (!buggy) { - buggy = 1; - printk("\n"); - } - realdelta = delta; - do_div(realdelta, one_usec); - if (tsc.values[i] < avg) - realdelta = -realdelta; - - if (realdelta) - printk(KERN_INFO "CPU#%d had %Ld usecs TSC " - "skew, fixed it up.\n", i, realdelta); - } - } - if (!buggy) - printk("passed.\n"); -} - -static void __cpuinit synchronize_tsc_ap(void) -{ - int i; - - /* - * Not every cpu is online at the time - * this gets called, so we first wait for the BP to - * finish SMP initialization: - */ - while (!atomic_read(&tsc.start_flag)) - cpu_relax(); - - for (i = 0; i < NR_LOOPS; i++) { - atomic_inc(&tsc.count_start); - while (atomic_read(&tsc.count_start) != num_booting_cpus()) - cpu_relax(); - - rdtscll(tsc.values[smp_processor_id()]); - if (i == NR_LOOPS-1) - write_tsc(0, 0); - - atomic_inc(&tsc.count_stop); - while (atomic_read(&tsc.count_stop) != num_booting_cpus()) - cpu_relax(); - } -} -#undef NR_LOOPS - extern void calibrate_delay(void); static atomic_t init_deasserted; @@ -446,12 +295,6 @@ static void __cpuinit smp_callin(void) * Allow the master to continue. */ cpu_set(cpuid, cpu_callin_map); - - /* - * Synchronize the TSC with the BP - */ - if (cpu_has_tsc && cpu_khz && !tsc_sync_disabled) - synchronize_tsc_ap(); } static int cpucount; @@ -554,6 +397,11 @@ static void __cpuinit start_secondary(void *unused) smp_callin(); while (!cpu_isset(smp_processor_id(), smp_commenced_mask)) rep_nop(); + /* + * Check TSC synchronization with the BP: + */ + check_tsc_sync_target(); + setup_secondary_clock(); if (nmi_watchdog == NMI_IO_APIC) { disable_8259A_irq(0); @@ -1125,8 +973,6 @@ static int __cpuinit __smp_prepare_cpu(int cpu) info.cpu = cpu; INIT_WORK(&info.task, do_warm_boot_cpu); - tsc_sync_disabled = 1; - /* init low mem mapping */ clone_pgd_range(swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS, min_t(unsigned long, KERNEL_PGD_PTRS, USER_PGD_PTRS)); @@ -1134,7 +980,6 @@ static int __cpuinit __smp_prepare_cpu(int cpu) schedule_work(&info.task); wait_for_completion(&done); - tsc_sync_disabled = 0; zap_low_mappings(); ret = 0; exit: @@ -1331,12 +1176,6 @@ static void __init smp_boot_cpus(unsigned int max_cpus) smpboot_setup_io_apic(); setup_boot_clock(); - - /* - * Synchronize the TSC with the AP - */ - if (cpu_has_tsc && cpucount && cpu_khz) - synchronize_tsc_bp(); } /* These are wrappers to interface to the new boot process. Someone @@ -1471,9 +1310,16 @@ int __cpuinit __cpu_up(unsigned int cpu) } local_irq_enable(); + per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; /* Unleash the CPU! */ cpu_set(cpu, smp_commenced_mask); + + /* + * Check TSC synchronization with the AP: + */ + check_tsc_sync_source(cpu); + while (!cpu_isset(cpu, cpu_online_map)) cpu_relax(); |