Re: [RFC v2 PATCH 05/17] mm: Routines to determine max anon folio allocation order

From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Ryan Roberts <ryan.roberts@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Yu Zhao <yuzhao@google.com>,
	"Yin, Fengwei" <fengwei.yin@intel.com>,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC v2 PATCH 05/17] mm: Routines to determine max anon folio allocation order
Date: Fri, 14 Apr 2023 17:09:48 +0300	[thread overview]
Message-ID: <20230414140948.7pcaz6niyr2tpa7s@box.shutemov.name> (raw)
In-Reply-To: <20230414130303.2345383-6-ryan.roberts@arm.com>

On Fri, Apr 14, 2023 at 02:02:51PM +0100, Ryan Roberts wrote:
> For variable-order anonymous folios, we want to tune the order that we
> prefer to allocate based on the vma. Add the routines to manage that
> heuristic.
> 
> TODO: Currently we always use the global maximum. Add per-vma logic!
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
>  include/linux/mm.h | 5 +++++
>  mm/memory.c        | 8 ++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index cdb8c6031d0f..cc8d0b239116 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3674,4 +3674,9 @@ madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
>  }
>  #endif
> 
> +/*
> + * TODO: Should this be set per-architecture?
> + */
> +#define ANON_FOLIO_ORDER_MAX	4
> +

I think it has to be derived from size in bytes, not directly specifies
page order. For 4K pages, order 4 is 64k and for 64k pages it is 1M.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov