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+/******************************************************************************
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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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+
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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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+
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+#include <asm/xen/hypervisor.h>
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+
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+#include <xen/interface/vcpu.h>
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+
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+#include "../kernel/fsyscall_gtod_data.h"
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+
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+DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
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+DEFINE_PER_CPU(unsigned long, processed_stolen_time);
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+DEFINE_PER_CPU(unsigned long, processed_blocked_time);
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+
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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(runstate, cpu);
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+ int rc;
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+
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+ memset(runstate, 0, sizeof(*runstate));
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+
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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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+
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+ per_cpu(processed_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
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+ per_cpu(processed_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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+/*
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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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+
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+ BUG_ON(preemptible());
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+
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+ state = &__get_cpu_var(runstate);
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+
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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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+
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+#define NS_PER_TICK (1000000000LL/HZ)
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+
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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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+
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+ get_runstate_snapshot(&runstate);
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+
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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(processed_blocked_time, cpu)))
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+ blocked = 0;
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+
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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(processed_stolen_time, cpu)))
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+ stolen = 0;
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+
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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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+
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+ do_div(stolentick, NS_PER_TICK);
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+ stolentick++;
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+
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+ do_div(stolen, NS_PER_TICK);
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+
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+ if (stolen > stolentick)
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+ stolen = stolentick;
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+
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+ stolentick -= stolen;
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+ do_div(blocked, NS_PER_TICK);
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+
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+ if (blocked > stolentick)
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+ blocked = stolentick;
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+
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+ if (stolen > 0 || blocked > 0) {
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+ account_steal_time(NULL, jiffies_to_cputime(stolen));
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+ account_steal_time(idle_task(cpu), jiffies_to_cputime(blocked));
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+ run_local_timers();
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+
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+ if (rcu_pending(cpu))
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+ rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
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+
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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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+
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+ if (cpu == time_keeper_id) {
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+ write_seqlock(&xtime_lock);
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+ do_timer(stolen + blocked);
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+ local_cpu_data->itm_next = delta_itm + new_itm;
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+ write_sequnlock(&xtime_lock);
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+ } else {
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+ local_cpu_data->itm_next = delta_itm + new_itm;
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+ }
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+ per_cpu(processed_stolen_time, cpu) += NS_PER_TICK * stolen;
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+ per_cpu(processed_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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+
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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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+
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+ return 0;
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+}
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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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+
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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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+
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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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+};
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Isaku Yamahata