Re: [PATCH v4 01/11] powerpc/mm: Adds counting method to monitor lockless pgtable walks

John Hubbard
2019-09-29T23:17:20Z

On 9/29/19 3:40 PM, John Hubbard wrote:
> On 9/27/19 4:39 PM, Leonardo Bras wrote:
...
> +config LOCKLESS_PAGE_TABLE_WALK_TRACKING
> +    bool "Tracking (and optimization) of lockless page table walkers"
> +    default n
> +
> +    help
> +      Maintain a reference count of active lockless page table
> +      walkers. This adds 4 bytes to struct mm size, and two atomic
> +      operations to calls such as get_user_pages_fast(). Some
> +      architectures can optimize page table operations if this
> +      is enabled.
> +
>  endmenu

Actually, the above should be an internal-only config option (PPC arch can
auto-select it), so just:

+config LOCKLESS_PAGE_TABLE_WALK_TRACKING
+ bool

...because it's entirely up to other code (as opposed to other people)
as to whether this should be selected.

I got carried away. :)

thanks,
--
John Hubbard
NVIDIA