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x86/xen/time: set pvclock flags on xen_time_init()

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Specifically check for PVCLOCK_TSC_STABLE_BIT and if this bit is set,
then set it too on pvclock flags. This allows Xen clocksource to use it
and thus speeding up xen_clocksource_read() callers (i.e. sched_clock())

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Joao Martins 2017-11-08 17:19:56 +00:00 committed by Boris Ostrovsky
parent 9f08890ab9
commit b888808093
1 changed files with 9 additions and 0 deletions
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9
arch/x86/xen/time.c
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@ -372,6 +372,7 @@ static const struct pv_time_ops xen_time_ops __initconst = {
static void __init xen_time_init(void)
{
struct pvclock_vcpu_time_info *pvti;
int cpu = smp_processor_id();
struct timespec tp;
@ -395,6 +396,14 @@ static void __init xen_time_init(void)
setup_force_cpu_cap(X86_FEATURE_TSC);
/*
* We check ahead on the primary time info if this
* bit is supported hence speeding up Xen clocksource.
*/
pvti = &__this_cpu_read(xen_vcpu)->time;
if (pvti->flags & PVCLOCK_TSC_STABLE_BIT)
pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
xen_setup_runstate_info(cpu);
xen_setup_timer(cpu);
xen_setup_cpu_clockevents();