linux-kernel - Re: [linux-next PATCH 1/2] mm: khugepaged: add exceed_max_ptes

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Date:   Fri, 1 May 2020 00:59:32 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     kirill.shutemov@...ux.intel.com, hughd@...gle.com,
        aarcange@...hat.com, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [linux-next PATCH 1/2] mm: khugepaged: add exceed_max_ptes_*
 helpers

On Thu, Apr 30, 2020 at 06:56:21AM +0800, Yang Shi wrote:
> The max_ptes_{swap|none|shared} are defined to tune the behavior of
> khugepaged.  The are checked at a couple of places with open coding.
> Replace the opencoding to exceed_pax_ptes_{swap|none_shared} helpers to
> improve the readability.
> 
> Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
> ---
>  mm/khugepaged.c | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index a02a4c5..0c8d30b 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -339,6 +339,21 @@ struct attribute_group khugepaged_attr_group = {
>  };
>  #endif /* CONFIG_SYSFS */
>  
> +static inline bool exceed_max_ptes_none(unsigned int *nr_ptes)
> +{
> +	return (++(*nr_ptes) > khugepaged_max_ptes_none);
> +}
> +
> +static inline bool exceed_max_ptes_swap(unsigned int *nr_ptes)
> +{
> +	return (++(*nr_ptes) > khugepaged_max_ptes_swap);
> +}
> +
> +static inline bool exceed_max_ptes_shared(unsigned int *nr_ptes)
> +{
> +	return (++(*nr_ptes) > khugepaged_max_ptes_shared);
> +}
> +

Frankly, I find this ugly and confusing. Open-coded version is more
readable to me.

-- 
 Kirill A. Shutemov