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AJvYcCWE4grlioWU7HuHsPtL4ilrUST0YBK5CJt5Is2sdC8X7zSORUkJvOKvR64ZSNVXoj0eEmj9yRicSQ==@kvack.org X-Gm-Message-State: AOJu0YzkjF9t3rdEOaydkkXkiowvdm+utMnnOTqD/SZ8VftAmWQJkpDO /9MRBuLRnyU+dwIdgE61wyihAOQuLaPR27f47wZ27fYNp0GBmWxqyNtK2EUBqgI3bXzBgNvm9ns nF+/4GBjWlA== X-Google-Smtp-Source: AGHT+IH6b52t8Y3G9I/VM3O9T3BG3LQ5av9EpjvEbeZWHVReqQ1O01cg1qPmn/VCTv/2ZgjpEWHY5Uby+C28 X-Received: from pfbfb3.prod.google.com ([2002:a05:6a00:2d83:b0:736:9d24:ae31]) (user=jyescas job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:a06:b0:736:5c8e:baaa with SMTP id d2e1a72fcca58-742acc8e94cmr25591985b3a.2.1747781989947; Tue, 20 May 2025 15:59:49 -0700 (PDT) Date: Tue, 20 May 2025 15:59:24 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.49.0.1112.g889b7c5bd8-goog Message-ID: <20250520225945.991229-1-jyescas@google.com> Subject: [PATCH v6] mm: Add CONFIG_PAGE_BLOCK_ORDER to select page block order From: Juan Yescas To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Juan Yescas , Zi Yan , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: tjmercier@google.com, isaacmanjarres@google.com, kaleshsingh@google.com, masahiroy@kernel.org, Minchan Kim Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 3E8EB140004 X-Stat-Signature: 3q5m79nwap7jdwsnhieztym94869dgmk X-HE-Tag: 1747781991-360124 X-HE-Meta: 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 7AKg4uiW 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 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: 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. For example, in ARM, the CMA alignment requirement when: - CONFIG_ARCH_FORCE_MAX_ORDER default value is used - CONFIG_TRANSPARENT_HUGEPAGE is set: PAGE_SIZE | MAX_PAGE_ORDER | pageblock_order | CMA_MIN_ALIGNMENT_BYTES ----------------------------------------------------------------------- 4KiB | 10 | 10 | 4KiB * (2 ^ 10) = 4MiB 16Kib | 11 | 11 | 16KiB * (2 ^ 11) = 32MiB 64KiB | 13 | 13 | 64KiB * (2 ^ 13) = 512MiB There are some extreme cases for the CMA alignment requirement when: - CONFIG_ARCH_FORCE_MAX_ORDER maximum value is set - CONFIG_TRANSPARENT_HUGEPAGE is NOT set: - CONFIG_HUGETLB_PAGE is NOT set PAGE_SIZE | MAX_PAGE_ORDER | pageblock_order | CMA_MIN_ALIGNMENT_BYTES ------------------------------------------------------------------------ 4KiB | 15 | 15 | 4KiB * (2 ^ 15) = 128MiB 16Kib | 13 | 13 | 16KiB * (2 ^ 13) = 128MiB 64KiB | 13 | 13 | 64KiB * (2 ^ 13) = 512MiB This affects the CMA reservations for the drivers. If a driver in a 4KiB kernel needs 4MiB of CMA memory, in a 16KiB kernel, the minimal reservation has to be 32MiB due to the alignment requirements: reserved-memory { ... cma_test_reserve: cma_test_reserve { compatible = "shared-dma-pool"; size = <0x0 0x400000>; /* 4 MiB */ ... }; }; reserved-memory { ... cma_test_reserve: cma_test_reserve { compatible = "shared-dma-pool"; size = <0x0 0x2000000>; /* 32 MiB */ ... }; }; Solution: Add a new config CONFIG_PAGE_BLOCK_ORDER that allows to set the page block order in all the architectures. The maximum page block order will be given by ARCH_FORCE_MAX_ORDER. By default, CONFIG_PAGE_BLOCK_ORDER will have the same value that ARCH_FORCE_MAX_ORDER. This will make sure that current kernel configurations won't be affected by this change. It is a opt-in change. This patch will allow to have the same CMA alignment requirements for large page sizes (16KiB, 64KiB) as that in 4kb kernels by setting a lower pageblock_order. Tests: - Verified that HugeTLB pages work when pageblock_order is 1, 7, 10 on 4k and 16k kernels. - Verified that Transparent Huge Pages work when pageblock_order is 1, 7, 10 on 4k and 16k kernels. - Verified that dma-buf heaps allocations work when pageblock_order is 1, 7, 10 on 4k and 16k kernels. Benchmarks: The benchmarks compare 16kb kernels with pageblock_order 10 and 7. The reason for the pageblock_order 7 is because this value makes the min CMA alignment requirement the same as that in 4kb kernels (2MB). - Perform 100K dma-buf heaps (/dev/dma_heap/system) allocations of SZ_8M, SZ_4M, SZ_2M, SZ_1M, SZ_64, SZ_8, SZ_4. Use simpleperf (https://developer.android.com/ndk/guides/simpleperf) to measure the # of instructions and page-faults on 16k kernels. The benchmark was executed 10 times. The averages are below: # instructions | #page-faults order 10 | order 7 | order 10 | order 7 -------------------------------------------------------- 13,891,765,770 | 11,425,777,314 | 220 | 217 14,456,293,487 | 12,660,819,302 | 224 | 219 13,924,261,018 | 13,243,970,736 | 217 | 221 13,910,886,504 | 13,845,519,630 | 217 | 221 14,388,071,190 | 13,498,583,098 | 223 | 224 13,656,442,167 | 12,915,831,681 | 216 | 218 13,300,268,343 | 12,930,484,776 | 222 | 218 13,625,470,223 | 14,234,092,777 | 219 | 218 13,508,964,965 | 13,432,689,094 | 225 | 219 13,368,950,667 | 13,683,587,37 | 219 | 225 ------------------------------------------------------------------- 13,803,137,433 | 13,131,974,268 | 220 | 220 Averages There were 4.85% #instructions when order was 7, in comparison with order 10. 13,803,137,433 - 13,131,974,268 = -671,163,166 (-4.86%) The number of page faults in order 7 and 10 were the same. These results didn't show any significant regression when the pageblock_order is set to 7 on 16kb kernels. - Run speedometer 3.1 (https://browserbench.org/Speedometer3.1/) 5 times on the 16k kernels with pageblock_order 7 and 10. order 10 | order 7 | order 7 - order 10 | (order 7 - order 10) % ------------------------------------------------------------------- 15.8 | 16.4 | 0.6 | 3.80% 16.4 | 16.2 | -0.2 | -1.22% 16.6 | 16.3 | -0.3 | -1.81% 16.8 | 16.3 | -0.5 | -2.98% 16.6 | 16.8 | 0.2 | 1.20% ------------------------------------------------------------------- 16.44 16.4 -0.04 -0.24% Averages The results didn't show any significant regression when the pageblock_order is set to 7 on 16kb kernels. Cc: Andrew Morton Cc: Vlastimil Babka Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: David Hildenbrand CC: Mike Rapoport Cc: Zi Yan Cc: Suren Baghdasaryan Cc: Minchan Kim Signed-off-by: Juan Yescas Acked-by: Zi Yan --- Changes in v6: - Applied the change provided by Zi Yan to fix the Kconfig. The change consists in evaluating to true or false in the if expression for range: range 1 if . Changes in v5: - Remove the ranges for CONFIG_PAGE_BLOCK_ORDER. The ranges with config definitions don't work in Kconfig, for example (range 1 MY_CONFIG). - Add PAGE_BLOCK_ORDER_MANUAL config for the page block order number. The default value was not defined. - Fix typos reported by Andrew. - Test default configs in powerpc. Changes in v4: - Set PAGE_BLOCK_ORDER in incluxe/linux/mmzone.h to validate that MAX_PAGE_ORDER >= PAGE_BLOCK_ORDER at compile time. - This change fixes the warning in: https://lore.kernel.org/oe-kbuild-all/202505091548.FuKO4b4v-lkp@intel.com/ Changes in v3: - Rename ARCH_FORCE_PAGE_BLOCK_ORDER to PAGE_BLOCK_ORDER as per Matthew's suggestion. - Update comments in pageblock-flags.h for pageblock_order value when THP or HugeTLB are not used. Changes in v2: - Add Zi's Acked-by tag. - Move ARCH_FORCE_PAGE_BLOCK_ORDER config to mm/Kconfig as per Zi and Matthew suggestion so it is available to all the architectures. - Set ARCH_FORCE_PAGE_BLOCK_ORDER to 10 by default when ARCH_FORCE_MAX_ORDER is not available. include/linux/mmzone.h | 16 ++++++++++++++++ include/linux/pageblock-flags.h | 8 ++++---- mm/Kconfig | 34 +++++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+), 4 deletions(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 6ccec1bf2896..05610337bbb6 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -37,6 +37,22 @@ #define NR_PAGE_ORDERS (MAX_PAGE_ORDER + 1) +/* Defines the order for the number of pages that have a migrate type. */ +#ifndef CONFIG_PAGE_BLOCK_ORDER +#define PAGE_BLOCK_ORDER MAX_PAGE_ORDER +#else +#define PAGE_BLOCK_ORDER CONFIG_PAGE_BLOCK_ORDER +#endif /* CONFIG_PAGE_BLOCK_ORDER */ + +/* + * The MAX_PAGE_ORDER, which defines the max order of pages to be allocated + * by the buddy allocator, has to be larger or equal to the PAGE_BLOCK_ORDER, + * which defines the order for the number of pages that can have a migrate type + */ +#if (PAGE_BLOCK_ORDER > MAX_PAGE_ORDER) +#error MAX_PAGE_ORDER must be >= PAGE_BLOCK_ORDER +#endif + /* * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed * costly to service. That is between allocation orders which should diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index fc6b9c87cb0a..e73a4292ef02 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -41,18 +41,18 @@ extern unsigned int pageblock_order; * Huge pages are a constant size, but don't exceed the maximum allocation * granularity. */ -#define pageblock_order MIN_T(unsigned int, HUGETLB_PAGE_ORDER, MAX_PAGE_ORDER) +#define pageblock_order MIN_T(unsigned int, HUGETLB_PAGE_ORDER, PAGE_BLOCK_ORDER) #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */ #elif defined(CONFIG_TRANSPARENT_HUGEPAGE) -#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, MAX_PAGE_ORDER) +#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, PAGE_BLOCK_ORDER) #else /* CONFIG_TRANSPARENT_HUGEPAGE */ -/* If huge pages are not used, group by MAX_ORDER_NR_PAGES */ -#define pageblock_order MAX_PAGE_ORDER +/* If huge pages are not used, group by PAGE_BLOCK_ORDER */ +#define pageblock_order PAGE_BLOCK_ORDER #endif /* CONFIG_HUGETLB_PAGE */ diff --git a/mm/Kconfig b/mm/Kconfig index e113f713b493..13a5c4f6e6b6 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -989,6 +989,40 @@ config CMA_AREAS If unsure, leave the default value "8" in UMA and "20" in NUMA. +# +# Select this config option from the architecture Kconfig, if available, to set +# the max page order for physically contiguous allocations. +# +config ARCH_FORCE_MAX_ORDER + int + +# +# When ARCH_FORCE_MAX_ORDER is not defined, +# the default page block order is MAX_PAGE_ORDER (10) as per +# include/linux/mmzone.h. +# +config PAGE_BLOCK_ORDER + int "Page Block Order" + range 1 10 if ARCH_FORCE_MAX_ORDER = 0 + default 10 if ARCH_FORCE_MAX_ORDER = 0 + range 1 ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 + default ARCH_FORCE_MAX_ORDER if ARCH_FORCE_MAX_ORDER != 0 + 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 config allows overriding the default page block order when the + page block order is required to be smaller than ARCH_FORCE_MAX_ORDER + or MAX_PAGE_ORDER. + + Reducing pageblock order can negatively impact THP generation + success rate. If your workloads uses THP heavily, please use this + option with caution. + + Don't change if unsure. + config MEM_SOFT_DIRTY bool "Track memory changes" depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS -- 2.49.0.1112.g889b7c5bd8-goog