It is expected for sched_clock() to output data from 0, when system boots.
Add an offset xen_sched_clock_offset (similarly how it is done in other hypervisors i.e. kvm_sched_clock_offset) to count sched_clock() from 0, when time is first initialized.
Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Juergen Gross jgross@suse.com --- This is upstream commit 38669ba205d178d2d38bfd194a196d65a44d5af2. Needed for upstream commit 867cefb4cb1012f42cada1c7d1f35ac8dd276071. --- arch/x86/xen/time.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index efa81e736f43..8c0b2beb3f46 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -31,6 +31,8 @@ /* Xen may fire a timer up to this many ns early */ #define TIMER_SLOP 100000
+static u64 xen_sched_clock_offset __read_mostly; + /* Get the TSC speed from Xen */ static unsigned long xen_tsc_khz(void) { @@ -57,6 +59,11 @@ static u64 xen_clocksource_get_cycles(struct clocksource *cs) return xen_clocksource_read(); }
+static u64 xen_sched_clock(void) +{ + return xen_clocksource_read() - xen_sched_clock_offset; +} + static void xen_read_wallclock(struct timespec *ts) { struct shared_info *s = HYPERVISOR_shared_info; @@ -367,7 +374,7 @@ void xen_timer_resume(void) }
static const struct pv_time_ops xen_time_ops __initconst = { - .sched_clock = xen_clocksource_read, + .sched_clock = xen_sched_clock, .steal_clock = xen_steal_clock, };
@@ -505,6 +512,7 @@ static void __init xen_time_init(void)
void __ref xen_init_time_ops(void) { + xen_sched_clock_offset = xen_clocksource_read(); pv_time_ops = xen_time_ops;
x86_init.timers.timer_init = xen_time_init; @@ -547,6 +555,7 @@ void __init xen_hvm_init_time_ops(void) return; }
+ xen_sched_clock_offset = xen_clocksource_read(); pv_time_ops = xen_time_ops; x86_init.timers.setup_percpu_clockev = xen_time_init; x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;