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/******************************************************************************
* arch/ia64/xen/time.c
*
* Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
* VA Linux Systems Japan K.K.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/delay.h>
#include <linux/kernel_stat.h>
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/clocksource.h>
#include <asm/xen/hypervisor.h>
#include <xen/interface/vcpu.h>
#include "../kernel/fsyscall_gtod_data.h"
DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
DEFINE_PER_CPU(unsigned long, processed_stolen_time);
DEFINE_PER_CPU(unsigned long, processed_blocked_time);
/* taken from i386/kernel/time-xen.c */
static void xen_init_missing_ticks_accounting(int cpu)
{
struct vcpu_register_runstate_memory_area area;
struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
int rc;
memset(runstate, 0, sizeof(*runstate));
area.addr.v = runstate;
rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
&area);
WARN_ON(rc && rc != -ENOSYS);
per_cpu(processed_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
per_cpu(processed_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
+ runstate->time[RUNSTATE_offline];
}
/*
* Runstate accounting
*/
/* stolen from arch/x86/xen/time.c */
static void get_runstate_snapshot(struct vcpu_runstate_info *res)
{
u64 state_time;
struct vcpu_runstate_info *state;
BUG_ON(preemptible());
state = &__get_cpu_var(runstate);
/*
* The runstate info is always updated by the hypervisor on
* the current CPU, so there's no need to use anything
* stronger than a compiler barrier when fetching it.
*/
do {
state_time = state->state_entry_time;
rmb();
*res = *state;
rmb();
} while (state->state_entry_time != state_time);
}
#define NS_PER_TICK (1000000000LL/HZ)
static unsigned long
consider_steal_time(unsigned long new_itm)
{
unsigned long stolen, blocked;
unsigned long delta_itm = 0, stolentick = 0;
int cpu = smp_processor_id();
struct vcpu_runstate_info runstate;
struct task_struct *p = current;
get_runstate_snapshot(&runstate);
/*
* Check for vcpu migration effect
* In this case, itc value is reversed.
* This causes huge stolen value.
* This function just checks and reject this effect.
*/
if (!time_after_eq(runstate.time[RUNSTATE_blocked],
per_cpu(processed_blocked_time, cpu)))
blocked = 0;
if (!time_after_eq(runstate.time[RUNSTATE_runnable] +
runstate.time[RUNSTATE_offline],
per_cpu(processed_stolen_time, cpu)))
stolen = 0;
if (!time_after(delta_itm + new_itm, ia64_get_itc()))
stolentick = ia64_get_itc() - new_itm;
do_div(stolentick, NS_PER_TICK);
stolentick++;
do_div(stolen, NS_PER_TICK);
if (stolen > stolentick)
stolen = stolentick;
stolentick -= stolen;
do_div(blocked, NS_PER_TICK);
if (blocked > stolentick)
blocked = stolentick;
if (stolen > 0 || blocked > 0) {
account_steal_time(NULL, jiffies_to_cputime(stolen));
account_steal_time(idle_task(cpu), jiffies_to_cputime(blocked));
run_local_timers();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
scheduler_tick();
run_posix_cpu_timers(p);
delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
if (cpu == time_keeper_id) {
write_seqlock(&xtime_lock);
do_timer(stolen + blocked);
local_cpu_data->itm_next = delta_itm + new_itm;
write_sequnlock(&xtime_lock);
} else {
local_cpu_data->itm_next = delta_itm + new_itm;
}
per_cpu(processed_stolen_time, cpu) += NS_PER_TICK * stolen;
per_cpu(processed_blocked_time, cpu) += NS_PER_TICK * blocked;
}
return delta_itm;
}
static int xen_do_steal_accounting(unsigned long *new_itm)
{
unsigned long delta_itm;
delta_itm = consider_steal_time(*new_itm);
*new_itm += delta_itm;
if (time_after(*new_itm, ia64_get_itc()) && delta_itm)
return 1;
return 0;
}
static void xen_itc_jitter_data_reset(void)
{
u64 lcycle, ret;
do {
lcycle = itc_jitter_data.itc_lastcycle;
ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, 0);
} while (unlikely(ret != lcycle));
}
struct pv_time_ops xen_time_ops __initdata = {
.init_missing_ticks_accounting = xen_init_missing_ticks_accounting,
.do_steal_accounting = xen_do_steal_accounting,
.clocksource_resume = xen_itc_jitter_data_reset,
};
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