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| /* |
| * Copyright (C) 2001-2004 Jakub Jermar |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * - The name of the author may not be used to endorse or promote products |
| * derived from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** @addtogroup time |
| * @{ |
| */ |
| |
| /** |
| * @file |
| * @brief High-level clock interrupt handler. |
| * |
| * This file contains the clock() function which is the source |
| * of preemption. It is also responsible for executing expired |
| * timeouts. |
| */ |
| |
| #include <time/clock.h> |
| #include <time/timeout.h> |
| #include <arch/types.h> |
| #include <config.h> |
| #include <synch/spinlock.h> |
| #include <synch/waitq.h> |
| #include <func.h> |
| #include <proc/scheduler.h> |
| #include <cpu.h> |
| #include <arch.h> |
| #include <adt/list.h> |
| #include <atomic.h> |
| #include <proc/thread.h> |
| #include <sysinfo/sysinfo.h> |
| #include <arch/barrier.h> |
| |
| /* Pointers to public variables with time */ |
| struct ptime { |
| unative_t seconds1; |
| unative_t useconds; |
| unative_t seconds2; |
| }; |
| struct ptime *public_time; |
| /* Variable holding fragment of second, so that we would update |
| * seconds correctly |
| */ |
| static unative_t secfrag = 0; |
| |
| /** Initialize realtime clock counter |
| * |
| * The applications (and sometimes kernel) need to access accurate |
| * information about realtime data. We allocate 1 page with these |
| * data and update it periodically. |
| * |
| * |
| */ |
| void clock_counter_init(void) |
| { |
| void *faddr; |
| |
| faddr = frame_alloc(0, FRAME_ATOMIC); |
| if (!faddr) |
| panic("Cannot allocate page for clock"); |
| |
| public_time = (struct ptime *)PA2KA(faddr); |
| |
| /* TODO: We would need some arch dependent settings here */ |
| public_time->seconds1 = 0; |
| public_time->seconds2 = 0; |
| public_time->useconds = 0; |
| |
| sysinfo_set_item_val("clock.faddr", NULL, (unative_t)faddr); |
| } |
| |
| |
| /** Update public counters |
| * |
| * Update it only on first processor |
| * TODO: Do we really need so many write barriers? |
| */ |
| static void clock_update_counters(void) |
| { |
| if (CPU->id == 0) { |
| secfrag += 1000000/HZ; |
| if (secfrag >= 1000000) { |
| secfrag -= 1000000; |
| public_time->seconds1++; |
| write_barrier(); |
| public_time->useconds = secfrag; |
| write_barrier(); |
| public_time->seconds2 = public_time->seconds1; |
| } else |
| public_time->useconds += 1000000/HZ; |
| } |
| } |
| |
| /** Clock routine |
| * |
| * Clock routine executed from clock interrupt handler |
| * (assuming interrupts_disable()'d). Runs expired timeouts |
| * and preemptive scheduling. |
| * |
| */ |
| void clock(void) |
| { |
| link_t *l; |
| timeout_t *h; |
| timeout_handler_t f; |
| void *arg; |
| count_t missed_clock_ticks = CPU->missed_clock_ticks; |
| int i; |
| |
| /* |
| * To avoid lock ordering problems, |
| * run all expired timeouts as you visit them. |
| */ |
| for (i = 0; i <= missed_clock_ticks; i++) { |
| clock_update_counters(); |
| spinlock_lock(&CPU->timeoutlock); |
| while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) { |
| h = list_get_instance(l, timeout_t, link); |
| spinlock_lock(&h->lock); |
| if (h->ticks-- != 0) { |
| spinlock_unlock(&h->lock); |
| break; |
| } |
| list_remove(l); |
| f = h->handler; |
| arg = h->arg; |
| timeout_reinitialize(h); |
| spinlock_unlock(&h->lock); |
| spinlock_unlock(&CPU->timeoutlock); |
| |
| f(arg); |
| |
| spinlock_lock(&CPU->timeoutlock); |
| } |
| spinlock_unlock(&CPU->timeoutlock); |
| } |
| CPU->missed_clock_ticks = 0; |
| |
| /* |
| * Do CPU usage accounting and find out whether to preempt THREAD. |
| */ |
| |
| if (THREAD) { |
| uint64_t ticks; |
| |
| spinlock_lock(&CPU->lock); |
| CPU->needs_relink += 1 + missed_clock_ticks; |
| spinlock_unlock(&CPU->lock); |
| |
| spinlock_lock(&THREAD->lock); |
| if ((ticks = THREAD->ticks)) { |
| if (ticks >= 1 + missed_clock_ticks) |
| THREAD->ticks -= 1 + missed_clock_ticks; |
| else |
| THREAD->ticks = 0; |
| } |
| spinlock_unlock(&THREAD->lock); |
| |
| if (!ticks && !PREEMPTION_DISABLED) { |
| scheduler(); |
| } |
| } |
| |
| } |
| |
| /** @} |
| */ |