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ia64/pv_ops/xen/pv_time_ops: implement sched_clock.

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paravirtualize sched_clock.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Isaku Yamahata 2009-03-04 21:05:41 +09:00 committed by Tony Luck
parent f927da1786
commit 1aec1c558a
1 changed files with 48 additions and 0 deletions
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48
arch/ia64/xen/time.c
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@ -175,10 +175,58 @@ static void xen_itc_jitter_data_reset(void)
} while (unlikely(ret != lcycle));
}
/* based on xen_sched_clock() in arch/x86/xen/time.c. */
/*
* This relies on HAVE_UNSTABLE_SCHED_CLOCK. If it can't be defined,
* something similar logic should be implemented here.
*/
/*
* Xen sched_clock implementation. Returns the number of unstolen
* nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED
* states.
*/
static unsigned long long xen_sched_clock(void)
{
struct vcpu_runstate_info runstate;
unsigned long long now;
unsigned long long offset;
unsigned long long ret;
/*
* Ideally sched_clock should be called on a per-cpu basis
* anyway, so preempt should already be disabled, but that's
* not current practice at the moment.
*/
preempt_disable();
/*
* both ia64_native_sched_clock() and xen's runstate are
* based on mAR.ITC. So difference of them makes sense.
*/
now = ia64_native_sched_clock();
get_runstate_snapshot(&runstate);
WARN_ON(runstate.state != RUNSTATE_running);
offset = 0;
if (now > runstate.state_entry_time)
offset = now - runstate.state_entry_time;
ret = runstate.time[RUNSTATE_blocked] +
runstate.time[RUNSTATE_running] +
offset;
preempt_enable();
return ret;
}
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,
.sched_clock = xen_sched_clock,
};
/* Called after suspend, to resume time. */