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authorJoao Martins <joao.m.martins@oracle.com>2017-11-08 17:19:56 +0000
committerBoris Ostrovsky <boris.ostrovsky@oracle.com>2017-11-08 16:33:14 -0500
commitb888808093113ae7d63d213272d01fea4b8329ed (patch)
treee580648ce8a0fa9ec3820102855c32403313df5b
parent9f08890ab906abaf9d4c1bad8111755cbd302260 (diff)
downloadlinux-b888808093113ae7d63d213272d01fea4b8329ed.tar.bz2
x86/xen/time: set pvclock flags on xen_time_init()
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>
-rw-r--r--arch/x86/xen/time.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 244791ff8201..c96e61fd70e7 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -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();