minix/kernel/arch/i386/arch_clock.c
Tomas Hruby 0a55e63413 SMP - fixed IPI livelock
- two CPUs can issue IPI to each other now without any hazzard

- we must be able to handle synchronous scheduling IPIs from
  other CPUs when we are waiting for attention from another one.
  Otherwise we might livelock.

- necessary barriers to prevent reordering
2012-01-13 11:30:00 +00:00

366 lines
8.4 KiB
C

/* i386-specific clock functions. */
#include <machine/ports.h>
#include <minix/portio.h>
#include "kernel/kernel.h"
#include "kernel/clock.h"
#include "kernel/proc.h"
#include "kernel/interrupt.h"
#include <minix/u64.h>
#include "glo.h"
#include "profile.h"
#ifdef USE_APIC
#include "apic.h"
#endif
#include "spinlock.h"
#ifdef CONFIG_SMP
#include "kernel/smp.h"
#endif
#define CLOCK_ACK_BIT 0x80 /* PS/2 clock interrupt acknowledge bit */
/* Clock parameters. */
#define COUNTER_FREQ (2*TIMER_FREQ) /* counter frequency using square wave */
#define LATCH_COUNT 0x00 /* cc00xxxx, c = channel, x = any */
#define SQUARE_WAVE 0x36 /* ccaammmb, a = access, m = mode, b = BCD */
/* 11x11, 11 = LSB then MSB, x11 = sq wave */
#define TIMER_FREQ 1193182 /* clock frequency for timer in PC and AT */
#define TIMER_COUNT(freq) (TIMER_FREQ/(freq)) /* initial value for counter*/
PRIVATE irq_hook_t pic_timer_hook; /* interrupt handler hook */
PRIVATE unsigned probe_ticks;
PRIVATE u64_t tsc0, tsc1;
#define PROBE_TICKS (system_hz / 10)
PRIVATE unsigned tsc_per_ms[CONFIG_MAX_CPUS];
/*===========================================================================*
* init_8235A_timer *
*===========================================================================*/
PUBLIC int init_8253A_timer(const unsigned freq)
{
/* Initialize channel 0 of the 8253A timer to, e.g., 60 Hz,
* and register the CLOCK task's interrupt handler to be run
* on every clock tick.
*/
outb(TIMER_MODE, SQUARE_WAVE); /* run continuously */
outb(TIMER0, (TIMER_COUNT(freq) & 0xff)); /* timer low byte */
outb(TIMER0, TIMER_COUNT(freq) >> 8); /* timer high byte */
return OK;
}
/*===========================================================================*
* stop_8235A_timer *
*===========================================================================*/
PUBLIC void stop_8253A_timer(void)
{
/* Reset the clock to the BIOS rate. (For rebooting.) */
outb(TIMER_MODE, 0x36);
outb(TIMER0, 0);
outb(TIMER0, 0);
}
PRIVATE int calib_cpu_handler(irq_hook_t * UNUSED(hook))
{
u64_t tsc;
probe_ticks++;
read_tsc_64(&tsc);
if (probe_ticks == 1) {
tsc0 = tsc;
}
else if (probe_ticks == PROBE_TICKS) {
tsc1 = tsc;
}
/* just in case we are in an SMP single cpu fallback mode */
BKL_UNLOCK();
return 1;
}
PRIVATE void estimate_cpu_freq(void)
{
u64_t tsc_delta;
u64_t cpu_freq;
irq_hook_t calib_cpu;
/* set the probe, we use the legacy timer, IRQ 0 */
put_irq_handler(&calib_cpu, CLOCK_IRQ, calib_cpu_handler);
/* just in case we are in an SMP single cpu fallback mode */
BKL_UNLOCK();
/* set the PIC timer to get some time */
intr_enable();
/* loop for some time to get a sample */
while(probe_ticks < PROBE_TICKS) {
intr_enable();
}
intr_disable();
/* just in case we are in an SMP single cpu fallback mode */
BKL_LOCK();
/* remove the probe */
rm_irq_handler(&calib_cpu);
tsc_delta = sub64(tsc1, tsc0);
cpu_freq = mul64(div64u64(tsc_delta, PROBE_TICKS - 1), make64(system_hz, 0));
cpu_set_freq(cpuid, cpu_freq);
cpu_info[cpuid].freq = div64u(cpu_freq, 1000000);
BOOT_VERBOSE(cpu_print_freq(cpuid));
}
PUBLIC int init_local_timer(unsigned freq)
{
#ifdef USE_APIC
/* if we know the address, lapic is enabled and we should use it */
if (lapic_addr) {
unsigned cpu = cpuid;
tsc_per_ms[cpu] = div64u(cpu_get_freq(cpu), 1000);
lapic_set_timer_one_shot(1000000/system_hz);
} else
{
BOOT_VERBOSE(printf("Initiating legacy i8253 timer\n"));
#else
{
#endif
init_8253A_timer(freq);
estimate_cpu_freq();
/* always only 1 cpu in the system */
tsc_per_ms[0] = div64u(cpu_get_freq(0), 1000);
}
return 0;
}
PUBLIC void stop_local_timer(void)
{
#ifdef USE_APIC
if (lapic_addr) {
lapic_stop_timer();
apic_eoi();
} else
#endif
{
stop_8253A_timer();
}
}
PUBLIC void restart_local_timer(void)
{
#ifdef USE_APIC
if (lapic_addr) {
lapic_restart_timer();
}
#endif
}
PUBLIC int register_local_timer_handler(const irq_handler_t handler)
{
#ifdef USE_APIC
if (lapic_addr) {
/* Using APIC, it is configured in apic_idt_init() */
BOOT_VERBOSE(printf("Using LAPIC timer as tick source\n"));
} else
#endif
{
/* Using PIC, Initialize the CLOCK's interrupt hook. */
pic_timer_hook.proc_nr_e = NONE;
pic_timer_hook.irq = CLOCK_IRQ;
put_irq_handler(&pic_timer_hook, CLOCK_IRQ, handler);
}
return 0;
}
PUBLIC void cycles_accounting_init(void)
{
#ifdef CONFIG_SMP
unsigned cpu = cpuid;
#endif
read_tsc_64(get_cpu_var_ptr(cpu, tsc_ctr_switch));
make_zero64(get_cpu_var(cpu, cpu_last_tsc));
make_zero64(get_cpu_var(cpu, cpu_last_idle));
}
PUBLIC void context_stop(struct proc * p)
{
u64_t tsc, tsc_delta;
u64_t * __tsc_ctr_switch = get_cpulocal_var_ptr(tsc_ctr_switch);
#ifdef CONFIG_SMP
unsigned cpu = cpuid;
/*
* This function is called only if we switch from kernel to user or idle
* or back. Therefore this is a perfect location to place the big kernel
* lock which will hopefully disappear soon.
*
* If we stop accounting for KERNEL we must unlock the BKL. If account
* for IDLE we must not hold the lock
*/
if (p == proc_addr(KERNEL)) {
u64_t tmp;
read_tsc_64(&tsc);
tmp = sub64(tsc, *__tsc_ctr_switch);
kernel_ticks[cpu] = add64(kernel_ticks[cpu], tmp);
p->p_cycles = add64(p->p_cycles, tmp);
BKL_UNLOCK();
} else {
u64_t bkl_tsc;
atomic_t succ;
read_tsc_64(&bkl_tsc);
/* this only gives a good estimate */
succ = big_kernel_lock.val;
BKL_LOCK();
read_tsc_64(&tsc);
bkl_ticks[cpu] = add64(bkl_ticks[cpu], sub64(tsc, bkl_tsc));
bkl_tries[cpu]++;
bkl_succ[cpu] += !(!(succ == 0));
p->p_cycles = add64(p->p_cycles, sub64(tsc, *__tsc_ctr_switch));
#ifdef CONFIG_SMP
/*
* Since at the time we got a scheduling IPI we might have been
* waiting for BKL already, we may miss it due to a similar IPI to
* the cpu which is already waiting for us to handle its. This
* results in a live-lock of these two cpus.
*
* Therefore we always check if there is one pending and if so,
* we handle it straight away so the other cpu can continue and
* we do not deadlock.
*/
smp_sched_handler();
#endif
}
#else
read_tsc_64(&tsc);
p->p_cycles = add64(p->p_cycles, sub64(tsc, *__tsc_ctr_switch));
#endif
tsc_delta = sub64(tsc, *__tsc_ctr_switch);
if(kbill_ipc) {
kbill_ipc->p_kipc_cycles =
add64(kbill_ipc->p_kipc_cycles, tsc_delta);
kbill_ipc = NULL;
}
if(kbill_kcall) {
kbill_kcall->p_kcall_cycles =
add64(kbill_kcall->p_kcall_cycles, tsc_delta);
kbill_kcall = NULL;
}
/*
* deduct the just consumed cpu cycles from the cpu time left for this
* process during its current quantum. Skip IDLE and other pseudo kernel
* tasks
*/
if (p->p_endpoint >= 0) {
#if DEBUG_RACE
make_zero64(p->p_cpu_time_left);
#else
/* if (tsc_delta < p->p_cpu_time_left) in 64bit */
if (ex64hi(tsc_delta) < ex64hi(p->p_cpu_time_left) ||
(ex64hi(tsc_delta) == ex64hi(p->p_cpu_time_left) &&
ex64lo(tsc_delta) < ex64lo(p->p_cpu_time_left)))
p->p_cpu_time_left = sub64(p->p_cpu_time_left, tsc_delta);
else {
make_zero64(p->p_cpu_time_left);
}
#endif
}
*__tsc_ctr_switch = tsc;
}
PUBLIC void context_stop_idle(void)
{
int is_idle;
#ifdef CONFIG_SMP
unsigned cpu = cpuid;
#endif
is_idle = get_cpu_var(cpu, cpu_is_idle);
get_cpu_var(cpu, cpu_is_idle) = 0;
context_stop(get_cpulocal_var_ptr(idle_proc));
if (is_idle)
restart_local_timer();
#if SPROFILE
if (sprofiling)
get_cpulocal_var(idle_interrupted) = 1;
#endif
}
PUBLIC u64_t ms_2_cpu_time(unsigned ms)
{
return mul64u(tsc_per_ms[cpuid], ms);
}
PUBLIC unsigned cpu_time_2_ms(u64_t cpu_time)
{
return div64u(cpu_time, tsc_per_ms[cpuid]);
}
PUBLIC short cpu_load(void)
{
u64_t current_tsc, *current_idle;
u64_t tsc_delta, idle_delta, busy;
struct proc *idle;
short load;
#ifdef CONFIG_SMP
unsigned cpu = cpuid;
#endif
u64_t *last_tsc, *last_idle;
last_tsc = get_cpu_var_ptr(cpu, cpu_last_tsc);
last_idle = get_cpu_var_ptr(cpu, cpu_last_idle);
idle = get_cpu_var_ptr(cpu, idle_proc);;
read_tsc_64(&current_tsc);
current_idle = &idle->p_cycles; /* ptr to idle proc */
/* calculate load since last cpu_load invocation */
if (!is_zero64(*last_tsc)) {
tsc_delta = sub64(current_tsc, *last_tsc);
idle_delta = sub64(*current_idle, *last_idle);
busy = sub64(tsc_delta, idle_delta);
busy = mul64(busy, make64(100, 0));
load = ex64lo(div64(busy, tsc_delta));
if (load > 100)
load = 100;
} else
load = 0;
*last_tsc = current_tsc;
*last_idle = *current_idle;
return load;
}