hi,
i386 vcpu hotplug seems to work reliably but x86_64 does not and i think
i have discovered why. in x86-64, a cpu within a domu can be removed with
vcpu-set but subsequent calls do nothing.
after xenwatch_thread grabs the event triggered by the write to the
store, it calls the registered handler and never comes back.
eventually, __cpu_die in drivers/xen/core/smpboot.c spins while waiting for the
hypervisor to report that the vcpu is down:
while (HYPERVISOR_vcpu_op(VCPUOP_is_up, cpu, NULL)) {
current->state = TASK_UNINTERRUPTIBLE;
schedule_timeout(HZ/10);
}
the critical difference is that play_dead in arch/i386/process-xen.c and
arch/x86_64/process-xen.c differ. the i386 version makes a VCPUOP_down
call to the hypervisor while the x86_64 version schedules a
SCHEDOP_yield among other things.
plopping the i386 version (patch below) into x86_64/process-xen.c makes
hotplugging in x86_64 behavior like i386. does anyone know why the
x86_64 play_dead function is in the current state?
thanks,
ryan
Signed-off-by: Ryan Grimm <grimm@xxxxxxxxxx>
diff -r 974ed9f73641 linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c
--- a/linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c Wed Feb 8
16:27:32 2006
+++ b/linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c Wed Feb 8
09:32:46 2006
@@ -53,6 +53,7 @@
#include <asm/kdebug.h>
#include <xen/interface/dom0_ops.h>
#include <xen/interface/physdev.h>
+#include <xen/interface/vcpu.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/hardirq.h>
@@ -143,22 +144,7 @@
/* We halt the CPU with physical CPU hotplug */
static inline void play_dead(void)
{
- idle_task_exit();
- wbinvd();
- mb();
- /* Ack it */
- __get_cpu_var(cpu_state) = CPU_DEAD;
-
- /* We shouldn't have to disable interrupts while dead, but
- * some interrupts just don't seem to go away, and this makes
- * it "work" for testing purposes. */
- /* Death loop */
- while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
- HYPERVISOR_sched_op(SCHEDOP_yield, 0);
-
- local_irq_disable();
- __flush_tlb_all();
- cpu_set(smp_processor_id(), cpu_online_map);
+ HYPERVISOR_vcpu_op(VCPUOP_down, smp_processor_id(), NULL);
local_irq_enable();
}
#else
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home