tsc_disabled is set when notsc is passed as kernel parameter. The reason we
have notsc is to avoid timing problems on multi-socket systems. We already
have a mechanism, however, to detect and resolve these issues by invoking
tsc unstable path. Thus, make notsc to behave the same as tsc=unstable.
Signed-off-by: Pavel Tatashin <pasha.tatas...@oracle.com>
---
arch/x86/kernel/tsc.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 97907e152356..dbce6fa32aa9 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -37,11 +37,6 @@ EXPORT_SYMBOL(tsc_khz);
*/
static int __read_mostly tsc_unstable;
-/* native_sched_clock() is called before tsc_init(), so
- we must start with the TSC soft disabled to prevent
- erroneous rdtsc usage on !boot_cpu_has(X86_FEATURE_TSC) processors */
-static int __read_mostly tsc_disabled = -1;
-
static DEFINE_STATIC_KEY_FALSE(__use_tsc);
int tsc_clocksource_reliable;
@@ -247,8 +242,7 @@ EXPORT_SYMBOL_GPL(check_tsc_unstable);
#ifdef CONFIG_X86_TSC
int __init notsc_setup(char *str)
{
- pr_warn("Kernel compiled with CONFIG_X86_TSC, cannot disable TSC
completely\n");
- tsc_disabled = 1;
+ mark_tsc_unstable("boot parameter notsc");
return 1;
}
#else
@@ -1229,7 +1223,7 @@ static void tsc_refine_calibration_work(struct
work_struct *work)
static int __init init_tsc_clocksource(void)
{
- if (!boot_cpu_has(X86_FEATURE_TSC) || tsc_disabled > 0 || !tsc_khz)
+ if (!boot_cpu_has(X86_FEATURE_TSC) || !tsc_khz)
return 0;
if (tsc_clocksource_reliable)
@@ -1330,12 +1324,6 @@ void __init tsc_init(void)
set_cyc2ns_scale(tsc_khz, cpu, cyc);
}
- if (tsc_disabled > 0)
- return;
-
- /* now allow native_sched_clock() to use rdtsc */
-
- tsc_disabled = 0;
static_branch_enable(&__use_tsc);
if (!no_sched_irq_time)
@@ -1365,10 +1353,9 @@ void __init tsc_init(void)
unsigned long calibrate_delay_is_known(void)
{
int sibling, cpu = smp_processor_id();
- int constant_tsc = cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC);
const struct cpumask *mask = topology_core_cpumask(cpu);
- if (tsc_disabled || !constant_tsc || !mask)
+ if (!cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC) || !mask)
return 0;
sibling = cpumask_any_but(mask, cpu);
--
2.15.0
