From nobody Tue Dec 16 07:42:15 2025 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C3625680 for ; Mon, 5 May 2025 18:56:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746471409; cv=none; b=R0p2+wlgAVIxEyfSBRtJeM7S6KQfU16JUnF67otQDInEJ02xaMtQu08/6MIk4NJz9gzclDeeynmFV5ajXrmAOkoxt5FNlK+oqSJRIgiDx0G9FId3i3lJ4YHuJL51GWlvBFZrmDJh9on5XVe7AQorJY8S+J87SfTsn4UsgJUBZNc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746471409; c=relaxed/simple; bh=cywvJlGq8YiX76fb6CHleawHs766IY9MRthPt6ppZNo=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=pmjiGZjaPs+CJQOKxQxIIxVGcAPRHnoqEgH/yirWwpSNWbQla0JlGYkmbbO/ntT/+m2OjwlR9PvoY7s0doX5CliAtNa04IpilcT2puSLMCg/hfNgf17xndiECfRmapDjf3BpG8RFz3QwNFK1k6pDrdVDQcei27shcGBgTjPxi04= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jyescas.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Bw9RTNEd; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jyescas.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Bw9RTNEd" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-227ed471999so39936375ad.3 for ; Mon, 05 May 2025 11:56:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1746471407; x=1747076207; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=6BNCNLNBqTLFiZABlKrrM/g6NMQdulKPbXBoMUL/JjY=; b=Bw9RTNEdi+8fA+2+HKORPNelTEGZZ0hvnhMP+90L7TAwefMfFpxIHrg62LgM35jfxR UiJdu6yIrFf4swvXjZyqgUII1T3eHh7sw1BIYLtaEc0J5PT1G5nTs4y/Y7zSeMMLfoz6 6aGJcjp3nfqTyXC6eJK6+cI9WLjP6FwOu0FuGWhnXd2pDfxIb8YG+rNt5bAk6m/aj9Y0 4Bis68J1eH59Ym8V7SvkudHkBdjsfqaEY2O/UFu15/FypbRwc5nBTHAoRm+3m3RUQpUx 5wUA6Rd8/FFhSsrRRPamhHzvZx/JBE2QWubySNlBd6ntaSRb7KxRnXCpU+PRNedn3cg8 NGXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746471407; x=1747076207; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=6BNCNLNBqTLFiZABlKrrM/g6NMQdulKPbXBoMUL/JjY=; b=M7Y0ff3Rmrn5jtFYpgc8D4AUsrkZSkdS6itjtDQwdo9AsZHm4fK99UE/K39+DSPDhR I4PjLOilS7AvUqLyTB8PPWOIcK2/gTNZfyW9yBBrfoeQrwregezeVmkkBpnuu/IS/52+ DCoCkMZ40XpmTlSgZfNGvj3AGCMkED8A0+5lq4fmtz3W89+n/t1yA8qFQF58Ol0m7v4h 2f8qjutxt/ddIEzxInexk0xzwCfPMl6F/Xs4iMrHVn/2VYbxRhrnV5bEiNEFjNfShHbl NZoBHpxyOs3bwjDx2YiDv5Ayt+Fulo+CL8vrzRube1OzRxM8yrHEgvR6XevdunwKwWVh WJYg== X-Forwarded-Encrypted: i=1; AJvYcCUKjjmHkenPhY2l5xsSzdGhoa/bsfSejCpvnFl6QhjS51fXHUjvqzhEqGmTWU3YrQ++VhDefKtN776F2UQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yx+IT2dpOpgiV/DkiOlNxluBJzaUwkxnVpNURZX7nSwhc0vZE+H Fe4u68oRzQ8oi8qTfpyii2+j7gEounG9hb16cxREmL3R35ShRc1i0x0Tm8fRgAZbALXuKI4nDKm 8DHLhSw== X-Google-Smtp-Source: AGHT+IHbATH+UFKHmuflnNXF6L3MKgptfzvwV0w7sgXiMV/YNyXmoNWn04iFlytUbCgy7zpCzKr6OoOJpDdR X-Received: from plrs15.prod.google.com ([2002:a17:902:b18f:b0:223:49cb:8f99]) (user=jyescas job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1c3:b0:223:7006:4db2 with SMTP id d9443c01a7336-22e1031fc0emr257429655ad.31.1746471407328; Mon, 05 May 2025 11:56:47 -0700 (PDT) Date: Mon, 5 May 2025 11:56:21 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.49.0.967.g6a0df3ecc3-goog Message-ID: <20250505185642.2377724-1-jyescas@google.com> Subject: [PATCH v2] mm: Add ARCH_FORCE_PAGE_BLOCK_ORDER to select page block order From: Juan Yescas To: Andrew Morton , Juan Yescas , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: tjmercier@google.com, isaacmanjarres@google.com, surenb@google.com, kaleshsingh@google.com, Vlastimil Babka , "Liam R. Howlett" , Lorenzo Stoakes , David Hildenbrand , Mike Rapoport , Zi Yan , Minchan Kim Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Acked-by: Zi Yan ----------------------------------------------------------------------- 4KiB | 10 | 10 | 4KiB * (2 ^ 10) =3D 4MiB 16Kib | 11 | 11 | 16KiB * (2 ^ 11) =3D 32MiB 64KiB | 13 | 13 | 64KiB * (2 ^ 13) =3D 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) =3D 128MiB 16Kib | 13 | 13 | 16KiB * (2 ^ 13) =3D 128MiB 64KiB | 13 | 13 | 64KiB * (2 ^ 13) =3D 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 =3D "shared-dma-pool"; size =3D <0x0 0x400000>; /* 4 MiB */ ... }; }; reserved-memory { ... cma_test_reserve: cma_test_reserve { compatible =3D "shared-dma-pool"; size =3D <0x0 0x2000000>; /* 32 MiB */ ... }; }; Solution: Add a new config ARCH_FORCE_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, ARCH_FORCE_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 =3D -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 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/pageblock-flags.h | 12 +++++++++--- mm/Kconfig | 31 +++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+), 3 deletions(-) diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flag= s.h index fc6b9c87cb0a..ab3de96bb50c 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -28,6 +28,12 @@ enum pageblock_bits { NR_PAGEBLOCK_BITS }; =20 +#if defined(CONFIG_ARCH_FORCE_PAGE_BLOCK_ORDER) +#define PAGE_BLOCK_ORDER CONFIG_ARCH_FORCE_PAGE_BLOCK_ORDER +#else +#define PAGE_BLOCK_ORDER MAX_PAGE_ORDER +#endif /* CONFIG_ARCH_FORCE_PAGE_BLOCK_ORDER */ + #if defined(CONFIG_HUGETLB_PAGE) =20 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE @@ -41,18 +47,18 @@ 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_BLOC= K_ORDER) =20 #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */ =20 #elif defined(CONFIG_TRANSPARENT_HUGEPAGE) =20 -#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, MAX_PAGE_ORD= ER) +#define pageblock_order MIN_T(unsigned int, HPAGE_PMD_ORDER, PAGE_BLOCK_O= RDER) =20 #else /* CONFIG_TRANSPARENT_HUGEPAGE */ =20 /* If huge pages are not used, group by MAX_ORDER_NR_PAGES */ -#define pageblock_order MAX_PAGE_ORDER +#define pageblock_order PAGE_BLOCK_ORDER =20 #endif /* CONFIG_HUGETLB_PAGE */ =20 diff --git a/mm/Kconfig b/mm/Kconfig index e113f713b493..a118d187a3bf 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -989,6 +989,37 @@ config CMA_AREAS =20 If unsure, leave the default value "8" in UMA and "20" in NUMA. =20 +# +# Select this config option from the architecture Kconfig, if available, t= o 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 order is 10, as per +# include/linux/mmzone.h. +config ARCH_FORCE_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. + config MEM_SOFT_DIRTY bool "Track memory changes" depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS --=20 2.49.0.967.g6a0df3ecc3-goog