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Howlett" , Lorenzo Stoakes , David Hildenbrand , Mike Rapoport , Minchan Kim Subject: Re: [PATCH v3] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order Message-Id: <20250505181442.898f17e6edfce39bc9c4cde3@linux-foundation.org> In-Reply-To: <20250506002319.513795-1-jyescas@google.com> References: <20250506002319.513795-1-jyescas@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 22087100009 X-Stat-Signature: ork6zutgggjdeqp4b1bugrhr7q8cjxfw X-Rspam-User: X-HE-Tag: 1746494084-201019 X-HE-Meta: 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 ZA3b35A6 2YtyqbTnAZ0zyfFEvawGgqL/Fr1bbbw8dJahyiq2BqH+rGUT/RIjhkp0qrKplrwz/Y7Nr6Er3VAKAtDuH/aW707aQKxqSXUW+S8PUcSgg+rsn6JALaKuSnbgKBFhSEldq6CdU22EIfWJTRRmQ5eDUVsyw7E8Zu3aWkbqozf6czYcnVyzbHmBuEELY805BlpXtCm2AGOtmEsoA2IYNPfzfZAtxEBNXjfuFoYgrl1I1aQj8XFzYpJ7boTOVvASjLD+aa9c/QdWMK+DGqD7FV7WsUV+fm1rOZ2v7cq0bbtDvHLR4w/xbnwVVE2K6v0ZZJKVGhA9s X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 5 May 2025 17:22:58 -0700 Juan Yescas 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. Thanks, I'll add this for testing while we consider the proposal. > +# as per include/linux/mmzone.h. > +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 > + > + help > + The page block order refers to the power of two number of pages that > + are physically contiguous and can have a migrate type associated to > + them. The maximum size of the page block order is limited by > + ARCH_FORCE_MAX_ORDER. > + > + This option allows overriding the default setting when the page > + block order requires to be smaller than ARCH_FORCE_MAX_ORDER. > + > + Reducing pageblock order can negatively impact THP generation > + successful rate. If your workloads uses THP heavily, please use this > + option with caution. > + > + Don't change if unsure. > + I messed with the text a little. --- a/mm/Kconfig~mm-add-config_page_block_order-to-select-page-block-order-fix +++ a/mm/Kconfig @@ -1028,10 +1028,10 @@ config PAGE_BLOCK_ORDER ARCH_FORCE_MAX_ORDER. This option allows overriding the default setting when the page - block order requires to be smaller than ARCH_FORCE_MAX_ORDER. + block order is required to be smaller than ARCH_FORCE_MAX_ORDER. Reducing pageblock order can negatively impact THP generation - successful rate. If your workloads uses THP heavily, please use this + success rate. If your workloads uses THP heavily, please use this option with caution. Don't change if unsure. _