Re: [PATCH v4 15/16] locking/rwsem: Merge owner into count on x86-64
From: Peter Zijlstra
Date: Thu Apr 18 2019 - 10:28:50 EST
On Sat, Apr 13, 2019 at 01:22:58PM -0400, Waiman Long wrote:
> +#ifdef CONFIG_X86_64
> +#define RWSEM_MERGE_OWNER_TO_COUNT
> +#ifdef RWSEM_MERGE_OWNER_TO_COUNT
> +#ifdef __PHYSICAL_MASK_SHIFT
> +#define RWSEM_PA_MASK_SHIFT __PHYSICAL_MASK_SHIFT
> +#define RWSEM_PA_MASK_SHIFT 52
I really dislike how this hardcodes x86_64.
It would be much better to have a CONFIG variable that gives us the
PA_BITS. Then all an architecture needs to do is set that right.
So ARM64 could also use this -- provided we get that overflow thing