arch/ia64/xen/time.c

   1 /******************************************************************************
   2  * arch/ia64/xen/time.c
   3  *
   4  * Copyright (c) 2008 Isaku Yamahata <yamahata at valinux co jp>
   5  *                    VA Linux Systems Japan K.K.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  */
  22
  23 #include <linux/delay.h>
  24 #include <linux/kernel_stat.h>
  25 #include <linux/posix-timers.h>
  26 #include <linux/irq.h>
  27 #include <linux/clocksource.h>
  28
  29 #include <asm/xen/hypervisor.h>
  30
  31 #include <xen/interface/vcpu.h>
  32
  33 #include "../kernel/fsyscall_gtod_data.h"
  34
  35 DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
  36 DEFINE_PER_CPU(unsigned long, processed_stolen_time);
  37 DEFINE_PER_CPU(unsigned long, processed_blocked_time);
  38
  39 /* taken from i386/kernel/time-xen.c */
  40 static void xen_init_missing_ticks_accounting(int cpu)
  41 {
  42         struct vcpu_register_runstate_memory_area area;
  43         struct vcpu_runstate_info *runstate = &per_cpu(runstate, cpu);
  44         int rc;
  45
  46         memset(runstate, 0, sizeof(*runstate));
  47
  48         area.addr.v = runstate;
  49         rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
  50                                 &area);
  51         WARN_ON(rc && rc != -ENOSYS);
  52
  53         per_cpu(processed_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
  54         per_cpu(processed_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
  55                                             + runstate->time[RUNSTATE_offline];
  56 }
  57
  58 #define NS_PER_TICK (1000000000LL/HZ)
  59
  60 static unsigned long
  61 consider_steal_time(unsigned long new_itm)
  62 {
  63         unsigned long stolen, blocked, sched_time;
  64         unsigned long delta_itm = 0, stolentick = 0;
  65         int cpu = smp_processor_id();
  66         struct vcpu_runstate_info *runstate;
  67         struct task_struct *p = current;
  68
  69         runstate = &per_cpu(runstate, smp_processor_id());
  70
  71         do {
  72                 sched_time = runstate->state_entry_time;
  73                 mb();
  74                 stolen = runstate->time[RUNSTATE_runnable] +
  75                          runstate->time[RUNSTATE_offline] -
  76                          per_cpu(processed_stolen_time, cpu);
  77                 blocked = runstate->time[RUNSTATE_blocked] -
  78                           per_cpu(processed_blocked_time, cpu);
  79                 mb();
  80         } while (sched_time != runstate->state_entry_time);
  81
  82         /*
  83          * Check for vcpu migration effect
  84          * In this case, itc value is reversed.
  85          * This causes huge stolen value.
  86          * This function just checks and reject this effect.
  87          */
  88         if (!time_after_eq(runstate->time[RUNSTATE_blocked],
  89                            per_cpu(processed_blocked_time, cpu)))
  90                 blocked = 0;
  91
  92         if (!time_after_eq(runstate->time[RUNSTATE_runnable] +
  93                            runstate->time[RUNSTATE_offline],
  94                            per_cpu(processed_stolen_time, cpu)))
  95                 stolen = 0;
  96
  97         if (!time_after(delta_itm + new_itm, ia64_get_itc()))
  98                 stolentick = ia64_get_itc() - delta_itm - new_itm;
  99
 100         do_div(stolentick, NS_PER_TICK);
 101         stolentick++;
 102
 103         do_div(stolen, NS_PER_TICK);
 104
 105         if (stolen > stolentick)
 106                 stolen = stolentick;
 107
 108         stolentick -= stolen;
 109         do_div(blocked, NS_PER_TICK);
 110
 111         if (blocked > stolentick)
 112                 blocked = stolentick;
 113
 114         if (stolen > 0 || blocked > 0) {
 115                 account_steal_time(NULL, jiffies_to_cputime(stolen));
 116                 account_steal_time(idle_task(cpu), jiffies_to_cputime(blocked));
 117                 run_local_timers();
 118
 119                 if (rcu_pending(cpu))
 120                         rcu_check_callbacks(cpu, user_mode(get_irq_regs()));
 121
 122                 scheduler_tick();
 123                 run_posix_cpu_timers(p);
 124                 delta_itm += local_cpu_data->itm_delta * (stolen + blocked);
 125
 126                 if (cpu == time_keeper_id) {
 127                         write_seqlock(&xtime_lock);
 128                         do_timer(stolen + blocked);
 129                         local_cpu_data->itm_next = delta_itm + new_itm;
 130                         write_sequnlock(&xtime_lock);
 131                 } else {
 132                         local_cpu_data->itm_next = delta_itm + new_itm;
 133                 }
 134                 per_cpu(processed_stolen_time, cpu) += NS_PER_TICK * stolen;
 135                 per_cpu(processed_blocked_time, cpu) += NS_PER_TICK * blocked;
 136         }
 137         return delta_itm;
 138 }
 139
 140 static int xen_do_steal_accounting(unsigned long *new_itm)
 141 {
 142         unsigned long delta_itm;
 143         delta_itm = consider_steal_time(*new_itm);
 144         *new_itm += delta_itm;
 145         if (time_after(*new_itm, ia64_get_itc()) && delta_itm)
 146                 return 1;
 147
 148         return 0;
 149 }
 150
 151 static void xen_itc_jitter_data_reset(void)
 152 {
 153         u64 lcycle, ret;
 154
 155         do {
 156                 lcycle = itc_jitter_data.itc_lastcycle;
 157                 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, 0);
 158         } while (unlikely(ret != lcycle));
 159 }
 160
 161 struct pv_time_ops xen_time_ops __initdata = {
 162         .init_missing_ticks_accounting  = xen_init_missing_ticks_accounting,
 163         .do_steal_accounting            = xen_do_steal_accounting,
 164         .clocksource_resume             = xen_itc_jitter_data_reset,
 165 };