[Xen-devel] Re: [PATCH 13/14] x86/ticketlock: add slowpath logic

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 16.11.10 at 22:08, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> +static inline void __ticket_enter_slowpath(struct arch_spinlock *lock)
> +{
> +     if (sizeof(lock->tickets.tail) == sizeof(u8))
> +             asm (LOCK_PREFIX "orb %1, %0"
> +                  : "+m" (lock->tickets.tail)
> +                  : "i" (TICKET_SLOWPATH_FLAG) : "memory");
> +     else
> +             asm (LOCK_PREFIX "orw %1, %0"
> +                  : "+m" (lock->tickets.tail)
> +                  : "i" (TICKET_SLOWPATH_FLAG) : "memory");
> +}

Came only now to mind: Here and elsewhere, did you try using
%z0 to have gcc produce the opcode suffix character, rather
than having these somewhat ugly if()-s?

Jan


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