258 строки
6.4 KiB
C
258 строки
6.4 KiB
C
/******************************************************************************
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* arch/ia64/xen/time.c
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*
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* Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
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* VA Linux Systems Japan K.K.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <linux/delay.h>
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#include <linux/kernel_stat.h>
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#include <linux/posix-timers.h>
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#include <linux/irq.h>
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#include <linux/clocksource.h>
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#include <asm/timex.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/interface/vcpu.h>
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#include "../kernel/fsyscall_gtod_data.h"
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static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
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static DEFINE_PER_CPU(unsigned long, xen_stolen_time);
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static DEFINE_PER_CPU(unsigned long, xen_blocked_time);
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/* taken from i386/kernel/time-xen.c */
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static void xen_init_missing_ticks_accounting(int cpu)
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{
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struct vcpu_register_runstate_memory_area area;
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struct vcpu_runstate_info *runstate = &per_cpu(xen_runstate, cpu);
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int rc;
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memset(runstate, 0, sizeof(*runstate));
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area.addr.v = runstate;
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rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
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&area);
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WARN_ON(rc && rc != -ENOSYS);
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per_cpu(xen_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
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per_cpu(xen_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
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+ runstate->time[RUNSTATE_offline];
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}
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/*
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* Runstate accounting
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*/
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/* stolen from arch/x86/xen/time.c */
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static void get_runstate_snapshot(struct vcpu_runstate_info *res)
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{
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u64 state_time;
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struct vcpu_runstate_info *state;
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BUG_ON(preemptible());
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state = &__get_cpu_var(xen_runstate);
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/*
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* The runstate info is always updated by the hypervisor on
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* the current CPU, so there's no need to use anything
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* stronger than a compiler barrier when fetching it.
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*/
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do {
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state_time = state->state_entry_time;
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rmb();
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*res = *state;
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rmb();
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} while (state->state_entry_time != state_time);
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}
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#define NS_PER_TICK (1000000000LL/HZ)
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static unsigned long
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consider_steal_time(unsigned long new_itm)
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{
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unsigned long stolen, blocked;
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unsigned long delta_itm = 0, stolentick = 0;
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int cpu = smp_processor_id();
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struct vcpu_runstate_info runstate;
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struct task_struct *p = current;
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get_runstate_snapshot(&runstate);
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/*
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* Check for vcpu migration effect
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* In this case, itc value is reversed.
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* This causes huge stolen value.
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* This function just checks and reject this effect.
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*/
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if (!time_after_eq(runstate.time[RUNSTATE_blocked],
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per_cpu(xen_blocked_time, cpu)))
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blocked = 0;
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if (!time_after_eq(runstate.time[RUNSTATE_runnable] +
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runstate.time[RUNSTATE_offline],
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per_cpu(xen_stolen_time, cpu)))
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stolen = 0;
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if (!time_after(delta_itm + new_itm, ia64_get_itc()))
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stolentick = ia64_get_itc() - new_itm;
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do_div(stolentick, NS_PER_TICK);
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stolentick++;
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do_div(stolen, NS_PER_TICK);
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if (stolen > stolentick)
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stolen = stolentick;
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stolentick -= stolen;
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do_div(blocked, NS_PER_TICK);
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if (blocked > stolentick)
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blocked = stolentick;
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if (stolen > 0 || blocked > 0) {
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account_steal_ticks(stolen);
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account_idle_ticks(blocked);
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run_local_timers();
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rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
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scheduler_tick();
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run_posix_cpu_timers(p);
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delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
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if (cpu == time_keeper_id)
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xtime_update(stolen + blocked);
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local_cpu_data->itm_next = delta_itm + new_itm;
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per_cpu(xen_stolen_time, cpu) += NS_PER_TICK * stolen;
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per_cpu(xen_blocked_time, cpu) += NS_PER_TICK * blocked;
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}
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return delta_itm;
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}
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static int xen_do_steal_accounting(unsigned long *new_itm)
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{
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unsigned long delta_itm;
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delta_itm = consider_steal_time(*new_itm);
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*new_itm += delta_itm;
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if (time_after(*new_itm, ia64_get_itc()) && delta_itm)
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return 1;
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return 0;
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}
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static void xen_itc_jitter_data_reset(void)
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{
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u64 lcycle, ret;
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do {
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lcycle = itc_jitter_data.itc_lastcycle;
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ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, 0);
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} while (unlikely(ret != lcycle));
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}
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/* based on xen_sched_clock() in arch/x86/xen/time.c. */
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/*
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* This relies on HAVE_UNSTABLE_SCHED_CLOCK. If it can't be defined,
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* something similar logic should be implemented here.
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*/
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/*
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* Xen sched_clock implementation. Returns the number of unstolen
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* nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED
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* states.
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*/
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static unsigned long long xen_sched_clock(void)
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{
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struct vcpu_runstate_info runstate;
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unsigned long long now;
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unsigned long long offset;
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unsigned long long ret;
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/*
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* Ideally sched_clock should be called on a per-cpu basis
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* anyway, so preempt should already be disabled, but that's
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* not current practice at the moment.
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*/
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preempt_disable();
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/*
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* both ia64_native_sched_clock() and xen's runstate are
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* based on mAR.ITC. So difference of them makes sense.
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*/
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now = ia64_native_sched_clock();
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get_runstate_snapshot(&runstate);
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WARN_ON(runstate.state != RUNSTATE_running);
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offset = 0;
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if (now > runstate.state_entry_time)
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offset = now - runstate.state_entry_time;
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ret = runstate.time[RUNSTATE_blocked] +
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runstate.time[RUNSTATE_running] +
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offset;
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preempt_enable();
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return ret;
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}
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struct pv_time_ops xen_time_ops __initdata = {
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.init_missing_ticks_accounting = xen_init_missing_ticks_accounting,
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.do_steal_accounting = xen_do_steal_accounting,
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.clocksource_resume = xen_itc_jitter_data_reset,
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.sched_clock = xen_sched_clock,
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};
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/* Called after suspend, to resume time. */
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static void xen_local_tick_resume(void)
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{
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/* Just trigger a tick. */
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ia64_cpu_local_tick();
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touch_softlockup_watchdog();
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}
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void
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xen_timer_resume(void)
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{
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unsigned int cpu;
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xen_local_tick_resume();
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for_each_online_cpu(cpu)
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xen_init_missing_ticks_accounting(cpu);
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}
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static void ia64_cpu_local_tick_fn(void *unused)
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{
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xen_local_tick_resume();
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xen_init_missing_ticks_accounting(smp_processor_id());
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}
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void
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xen_timer_resume_on_aps(void)
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{
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smp_call_function(&ia64_cpu_local_tick_fn, NULL, 1);
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}
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