c554aef0e1
- pressing 'B' on the serial cnsole prints statistics for BKL per cpu. - 'b' resets the counters - it presents number of cycles each CPU spends in kernel, how many cycyles it spends spinning while waiting for the BKL - it shows optimistic estimation in how many cases we get the lock immediately without spinning. As the test is not atomic the lock may be already held by some other cpu before we actually try to acquire it.
253 lines
6 KiB
C
253 lines
6 KiB
C
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/* i386-specific clock functions. */
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#include <machine/ports.h>
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#include <minix/portio.h>
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#include "kernel/kernel.h"
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#include "kernel/clock.h"
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#include "kernel/proc.h"
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#include <minix/u64.h>
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#include "glo.h"
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#ifdef CONFIG_APIC
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#include "apic.h"
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#endif
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#include "spinlock.h"
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#define CLOCK_ACK_BIT 0x80 /* PS/2 clock interrupt acknowledge bit */
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/* Clock parameters. */
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#define COUNTER_FREQ (2*TIMER_FREQ) /* counter frequency using square wave */
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#define LATCH_COUNT 0x00 /* cc00xxxx, c = channel, x = any */
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#define SQUARE_WAVE 0x36 /* ccaammmb, a = access, m = mode, b = BCD */
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/* 11x11, 11 = LSB then MSB, x11 = sq wave */
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#define TIMER_FREQ 1193182 /* clock frequency for timer in PC and AT */
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#define TIMER_COUNT(freq) (TIMER_FREQ/(freq)) /* initial value for counter*/
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PRIVATE irq_hook_t pic_timer_hook; /* interrupt handler hook */
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PRIVATE unsigned probe_ticks;
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PRIVATE u64_t tsc0, tsc1;
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#define PROBE_TICKS (system_hz / 10)
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PRIVATE unsigned tsc_per_ms[CONFIG_MAX_CPUS];
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/*===========================================================================*
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* init_8235A_timer *
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*===========================================================================*/
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PUBLIC int init_8253A_timer(const unsigned freq)
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{
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/* Initialize channel 0 of the 8253A timer to, e.g., 60 Hz,
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* and register the CLOCK task's interrupt handler to be run
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* on every clock tick.
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*/
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outb(TIMER_MODE, SQUARE_WAVE); /* run continuously */
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outb(TIMER0, (TIMER_COUNT(freq) & 0xff)); /* timer low byte */
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outb(TIMER0, TIMER_COUNT(freq) >> 8); /* timer high byte */
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return OK;
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}
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/*===========================================================================*
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* stop_8235A_timer *
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*===========================================================================*/
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PUBLIC void stop_8253A_timer(void)
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{
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/* Reset the clock to the BIOS rate. (For rebooting.) */
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outb(TIMER_MODE, 0x36);
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outb(TIMER0, 0);
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outb(TIMER0, 0);
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}
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PRIVATE int calib_cpu_handler(irq_hook_t * UNUSED(hook))
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{
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u64_t tsc;
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probe_ticks++;
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read_tsc_64(&tsc);
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if (probe_ticks == 1) {
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tsc0 = tsc;
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}
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else if (probe_ticks == PROBE_TICKS) {
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tsc1 = tsc;
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}
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/* just in case we are in an SMP single cpu fallback mode */
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BKL_UNLOCK();
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return 1;
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}
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PRIVATE void estimate_cpu_freq(void)
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{
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u64_t tsc_delta;
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u64_t cpu_freq;
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irq_hook_t calib_cpu;
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/* set the probe, we use the legacy timer, IRQ 0 */
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put_irq_handler(&calib_cpu, CLOCK_IRQ, calib_cpu_handler);
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/* just in case we are in an SMP single cpu fallback mode */
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BKL_UNLOCK();
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/* set the PIC timer to get some time */
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intr_enable();
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/* loop for some time to get a sample */
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while(probe_ticks < PROBE_TICKS) {
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intr_enable();
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}
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intr_disable();
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/* just in case we are in an SMP single cpu fallback mode */
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BKL_LOCK();
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/* remove the probe */
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rm_irq_handler(&calib_cpu);
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tsc_delta = sub64(tsc1, tsc0);
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cpu_freq = mul64(div64u64(tsc_delta, PROBE_TICKS - 1), make64(system_hz, 0));
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cpu_set_freq(cpuid, cpu_freq);
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BOOT_VERBOSE(cpu_print_freq(cpuid));
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}
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PUBLIC int arch_init_local_timer(unsigned freq)
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{
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#ifdef CONFIG_APIC
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/* if we know the address, lapic is enabled and we should use it */
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if (lapic_addr) {
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unsigned cpu = cpuid;
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lapic_set_timer_periodic(freq);
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tsc_per_ms[cpu] = div64u(cpu_get_freq(cpu), 1000);
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} else
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{
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BOOT_VERBOSE(printf("Initiating legacy i8253 timer\n"));
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#else
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{
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#endif
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init_8253A_timer(freq);
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estimate_cpu_freq();
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/* always only 1 cpu in the system */
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tsc_per_ms[0] = div64u(cpu_get_freq(0), 1000);
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}
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return 0;
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}
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PUBLIC void arch_stop_local_timer(void)
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{
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#ifdef CONFIG_APIC
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if (lapic_addr) {
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lapic_stop_timer();
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} else
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#endif
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{
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stop_8253A_timer();
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}
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}
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PUBLIC int arch_register_local_timer_handler(const irq_handler_t handler)
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{
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#ifdef CONFIG_APIC
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if (lapic_addr) {
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/* Using APIC, it is configured in apic_idt_init() */
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BOOT_VERBOSE(printf("Using LAPIC timer as tick source\n"));
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} else
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#endif
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{
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/* Using PIC, Initialize the CLOCK's interrupt hook. */
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pic_timer_hook.proc_nr_e = NONE;
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pic_timer_hook.irq = CLOCK_IRQ;
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put_irq_handler(&pic_timer_hook, CLOCK_IRQ, handler);
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}
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return 0;
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}
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PUBLIC void cycles_accounting_init(void)
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{
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read_tsc_64(get_cpulocal_var_ptr(tsc_ctr_switch));
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}
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PUBLIC void context_stop(struct proc * p)
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{
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u64_t tsc, tsc_delta;
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u64_t * __tsc_ctr_switch = get_cpulocal_var_ptr(tsc_ctr_switch);
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read_tsc_64(&tsc);
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tsc_delta = sub64(tsc, *__tsc_ctr_switch);
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p->p_cycles = add64(p->p_cycles, tsc_delta);
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/*
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* deduct the just consumed cpu cycles from the cpu time left for this
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* process during its current quantum. Skip IDLE and other pseudo kernel
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* tasks
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*/
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if (p->p_endpoint >= 0) {
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#if DEBUG_RACE
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make_zero64(p->p_cpu_time_left);
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#else
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/* if (tsc_delta < p->p_cpu_time_left) in 64bit */
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if (tsc_delta.hi < p->p_cpu_time_left.hi ||
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(tsc_delta.hi == p->p_cpu_time_left.hi &&
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tsc_delta.lo < p->p_cpu_time_left.lo))
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p->p_cpu_time_left = sub64(p->p_cpu_time_left, tsc_delta);
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else {
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make_zero64(p->p_cpu_time_left);
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}
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#endif
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}
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/*
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* This function is called only if we switch from kernel to user or idle
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* or back. Therefore this is a perfect location to place the big kernel
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* lock which will hopefully disappear soon.
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*
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* If we stop accounting for KERNEL we must unlock the BKL. If account
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* for IDLE we must not hold the lock
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*/
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if (p == proc_addr(KERNEL)) {
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read_tsc_64(&tsc);
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p->p_cycles = add64(p->p_cycles, sub64(tsc, *__tsc_ctr_switch));
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BKL_UNLOCK();
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} else {
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u64_t bkl_tsc, tmp;
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unsigned cpu = cpuid;
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atomic_t succ;
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read_tsc_64(&bkl_tsc);
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/* this only gives a good estimate */
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succ = big_kernel_lock.val;
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BKL_LOCK();
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read_tsc_64(&tsc);
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bkl_ticks[cpu] = add64(bkl_ticks[cpu], sub64(tsc, bkl_tsc));
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bkl_tries[cpu]++;
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bkl_succ[cpu] += !(!(succ == 0));
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tmp = sub64(tsc, *__tsc_ctr_switch);
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kernel_ticks[cpu] = add64(kernel_ticks[cpu], tmp);
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p->p_cycles = add64(p->p_cycles, tmp);
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}
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*__tsc_ctr_switch = tsc;
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}
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PUBLIC void context_stop_idle(void)
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{
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context_stop(proc_addr(IDLE));
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}
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PUBLIC u64_t ms_2_cpu_time(unsigned ms)
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{
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return mul64u(tsc_per_ms[cpuid], ms);
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}
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