From: Andrew Morton <akpm@linux-foundation.org>
To: Juan Yescas <jyescas@google.com>
Cc: Zi Yan <ziy@nvidia.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
tjmercier@google.com, isaacmanjarres@google.com,
surenb@google.com, kaleshsingh@google.com,
Vlastimil Babka <vbabka@suse.cz>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
David Hildenbrand <david@redhat.com>,
Mike Rapoport <rppt@kernel.org>, Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH v3] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order
Date: Tue, 6 May 2025 00:01:33 -0700 [thread overview]
Message-ID: <20250506000133.ba44539dd517e4f54515751b@linux-foundation.org> (raw)
In-Reply-To: <20250506002319.513795-1-jyescas@google.com>
On Mon, 5 May 2025 17:22:58 -0700 Juan Yescas <jyescas@google.com> wrote:
> Problem: On large page size configurations (16KiB, 64KiB), the CMA
> alignment requirement (CMA_MIN_ALIGNMENT_BYTES) increases considerably,
> and this causes the CMA reservations to be larger than necessary.
> This means that system will have less available MIGRATE_UNMOVABLE and
> MIGRATE_RECLAIMABLE page blocks since MIGRATE_CMA can't fallback to them.
>
> The CMA_MIN_ALIGNMENT_BYTES increases because it depends on
> MAX_PAGE_ORDER which depends on ARCH_FORCE_MAX_ORDER. The value of
> ARCH_FORCE_MAX_ORDER increases on 16k and 64k kernels.
>
> ...
>
> +config PAGE_BLOCK_ORDER
> + int "Page Block Order"
> + range 1 10 if !ARCH_FORCE_MAX_ORDER
> + default 10 if !ARCH_FORCE_MAX_ORDER
> + range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER
> + default ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER
Do we really need to do this arithmetic within Kconfig? Would it be
cleaner to do this at runtime, presumably when calculating
pageblock_order?
next prev parent reply other threads:[~2025-05-06 7:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-06 0:22 Juan Yescas
2025-05-06 1:14 ` Andrew Morton
2025-05-06 6:53 ` Anshuman Khandual
2025-05-06 12:59 ` Zi Yan
2025-05-06 16:08 ` Juan Yescas
2025-05-06 7:01 ` Andrew Morton [this message]
2025-05-06 12:48 ` Vlastimil Babka
2025-05-06 23:50 ` Andrew Morton
2025-05-07 0:02 ` Zi Yan
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