diff --git a/kernel/arch/x86_64/cmos.c b/kernel/arch/x86_64/cmos.c
index b39f9c20..1593e49a 100644
--- a/kernel/arch/x86_64/cmos.c
+++ b/kernel/arch/x86_64/cmos.c
@@ -256,19 +256,27 @@ void arch_tick_others(void);
 
 static uint64_t time_slice_basis = 0;
 
-int cmos_time_stuff(struct regs *r) {
+static spin_lock_t clock_lock = { 0 };
+void arch_update_clock(void) {
 	uint64_t clock_ticks = read_tsc() / tsc_mhz;
 	uint64_t timer_ticks, timer_subticks;
+	spin_lock(clock_lock);
 	update_ticks(clock_ticks, &timer_ticks, &timer_subticks);
-	wakeup_sleepers(timer_ticks, timer_subticks);
-	irq_ack(0);
-
 	if (time_slice_basis + SUBSECONDS_PER_SECOND/4 <= clock_ticks) {
 		update_process_usage(clock_ticks - time_slice_basis, tsc_mhz);
 		time_slice_basis = clock_ticks;
 	}
+	spin_unlock(clock_lock);
+
+	wakeup_sleepers(timer_ticks, timer_subticks);
+
+}
+
+int cmos_time_stuff(struct regs *r) {
+	arch_update_clock();
+
+	irq_ack(0);
 
-	arch_tick_others();
 	switch_task(1);
 	asm volatile (
 		".global _ret_from_preempt_source\n"
diff --git a/kernel/arch/x86_64/idt.c b/kernel/arch/x86_64/idt.c
index e122ba4c..dce3cf1d 100644
--- a/kernel/arch/x86_64/idt.c
+++ b/kernel/arch/x86_64/idt.c
@@ -339,6 +339,8 @@ struct regs * isr_handler(struct regs * r) {
 			return r;
 		}
 		case 123: {
+			extern void arch_update_clock(void);
+			arch_update_clock();
 			switch_task(1);
 			return r;
 		}
diff --git a/kernel/arch/x86_64/smp.c b/kernel/arch/x86_64/smp.c
index 50019634..0294162b 100644
--- a/kernel/arch/x86_64/smp.c
+++ b/kernel/arch/x86_64/smp.c
@@ -10,6 +10,7 @@
 #include <kernel/printf.h>
 #include <kernel/misc.h>
 #include <kernel/args.h>
+#include <kernel/time.h>
 #include <kernel/multiboot.h>
 #include <kernel/arch/x86_64/acpi.h>
 #include <kernel/arch/x86_64/mmu.h>
@@ -123,6 +124,20 @@ void ap_main(void) {
 
 	/* Enable our spurious vector register */
 	*((volatile uint32_t*)(lapic_final + 0x0F0)) = 0x127;
+	*((volatile uint32_t*)(lapic_final + 0x320)) = 0x7b;
+	*((volatile uint32_t*)(lapic_final + 0x3e0)) = 1;
+
+	uint64_t before = arch_perf_timer();
+	*((volatile uint32_t*)(lapic_final + 0x380)) = 1000000;
+	while (*((volatile uint32_t*)(lapic_final + 0x390)));
+	uint64_t after = arch_perf_timer();
+
+	uint64_t ms = (after-before)/arch_cpu_mhz();
+	uint64_t target = 10000000000UL / ms;
+
+	*((volatile uint32_t*)(lapic_final + 0x3e0)) = 1;
+	*((volatile uint32_t*)(lapic_final + 0x320)) = 0x7b | 0x20000;
+	*((volatile uint32_t*)(lapic_final + 0x380)) = target;
 
 	/* Set our pml pointers */
 	this_core->current_pml = &init_page_region[0];