[PATCH] Add the vgetcpu vsyscall
This patch adds a vgetcpu vsyscall, which depending on the CPU RDTSCP
capability uses either the RDTSCP or CPUID to obtain a CPU and node
numbers and pass them to the program.
AK: Lots of changes over Vojtech's original code:
Better prototype for vgetcpu()
It's better to pass the cpu / node numbers as separate arguments
to avoid mistakes when going from SMP to NUMA.
Also add a fast time stamp based cache using a user supplied
argument to speed things more up.
Use fast method from Chuck Ebbert to retrieve node/cpu from
GDT limit instead of CPUID
Made sure RDTSCP init is always executed after node is known.
Drop printk
Signed-off-by: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 97b9e46d..560ed94 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -899,12 +899,8 @@
time_cpu_notifier(struct notifier_block *nb, unsigned long action, void *hcpu)
{
unsigned cpu = (unsigned long) hcpu;
- if (action == CPU_ONLINE &&
- cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP)) {
- unsigned p;
- p = smp_processor_id() | (cpu_to_node(smp_processor_id())<<12);
- write_rdtscp_aux(p);
- }
+ if (action == CPU_ONLINE)
+ vsyscall_set_cpu(cpu);
return NOTIFY_DONE;
}
@@ -993,6 +989,11 @@
if (unsynchronized_tsc())
notsc = 1;
+ if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
+ vgetcpu_mode = VGETCPU_RDTSCP;
+ else
+ vgetcpu_mode = VGETCPU_LSL;
+
if (vxtime.hpet_address && notsc) {
timetype = hpet_use_timer ? "HPET" : "PIT/HPET";
if (hpet_use_timer)