On Mon, Dec 13, 2004 at 01:12:19PM +0100, Michael Kukat wrote:
> 
> diff -Naru sys.orig/arch/xen/i386/locore.S sys/arch/xen/i386/locore.S
> --- sys.orig/arch/xen/i386/locore.S     2004-09-23 04:41:01.000000000 +0200
> +++ sys/arch/xen/i386/locore.S  2004-12-13 13:51:57.000000000 +0100
> @@ -1610,6 +1610,7 @@
>         jmp     idle_start
>  4:
>         movl    $__HYPERVISOR_yield,%eax
> +       movl    $0,%ebx
>         TRAP_INSTR
>  NENTRY(mpidle)
>  idle_start:
> 
> The symbol __HYPERVISOR_yield is somewhat misleading, as it is the operation
> for HYPERVISOR_sched_op, which has the value 8. SCHEDOP_yield (0) must go to
> ebx to tell Xen to yield.

This change makes an *enormous* difference in performance on one of the
TNF servers.  I will commit it and request a pullup for 2.1.

Thor