From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Rich Felker <dalias@libc.org>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Max Filippov <jcmvbkbc@gmail.com>, Guo Ren <guoren@kernel.org>,
linux-csky@vger.kernel.org, sparclinux@vger.kernel.org,
Will Deacon <will@kernel.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Russell King <linux@armlinux.org.uk>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Zi Yan <ziy@nvidia.com>,
linux-xtensa@linux-xtensa.org, Arnd Bergmann <arnd@arndb.de>,
linux-m68k@lists.linux-m68k.org,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Dinh Nguyen <dinguyen@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linuxppc-dev@lists.ozlabs.org,
"David S. Miller" <davem@davemloft.net>,
Mike Rapoport <rppt@kernel.org>
Subject: [PATCH v2 03/14] arm64: reword ARCH_FORCE_MAX_ORDER prompt and help text
Date: Fri, 24 Mar 2023 08:22:22 +0300 [thread overview]
Message-ID: <20230324052233.2654090-4-rppt@kernel.org> (raw)
In-Reply-To: <20230324052233.2654090-1-rppt@kernel.org>
From: "Mike Rapoport (IBM)" <rppt@kernel.org>
The prompt and help text of ARCH_FORCE_MAX_ORDER are not even close to
describe this configuration option.
Update both to actually describe what this option does.
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/arm64/Kconfig | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7324032af859..cdaf52ac4018 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1487,24 +1487,24 @@ config XEN
# 16K | 27 | 14 | 13 | 11 |
# 64K | 29 | 16 | 13 | 13 |
config ARCH_FORCE_MAX_ORDER
- int "Maximum zone order" if EXPERT && (ARM64_4K_PAGES || ARM64_16K_PAGES)
+ int "Order of maximal physically contiguous allocations" if ARM64_4K_PAGES || ARM64_16K_PAGES
default "13" if ARM64_64K_PAGES
default "11" if ARM64_16K_PAGES
default "10"
help
- The kernel memory allocator divides physically contiguous memory
- blocks into "zones", where each zone is a power of two number of
- pages. This option selects the largest power of two that the kernel
- keeps in the memory allocator. If you need to allocate very large
- blocks of physically contiguous memory, then you may need to
- increase this value.
+ The kernel page allocator limits the size of maximal physically
+ contiguous allocations. The limit is called MAX_ORDER and it
+ defines the maximal power of two of number of pages that can be
+ allocated as a single contiguous block. This option allows
+ overriding the default setting when ability to allocate very
+ large blocks of physically contiguous memory is required.
- We make sure that we can allocate up to a HugePage size for each configuration.
- Hence we have :
- MAX_ORDER = PMD_SHIFT - PAGE_SHIFT => PAGE_SHIFT - 3
+ The maximal size of allocation cannot exceed the size of the
+ section, so the value of MAX_ORDER should satisfy
- However for 4K, we choose a higher default value, 10 as opposed to 9, giving us
- 4M allocations matching the default size used by generic code.
+ MAX_ORDER + PAGE_SHIFT <= SECTION_SIZE_BITS
+
+ Don't change if unsure.
config UNMAP_KERNEL_AT_EL0
bool "Unmap kernel when running in userspace (aka \"KAISER\")" if EXPERT
--
2.35.1
next prev parent reply other threads:[~2023-03-24 5:26 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-24 5:22 [PATCH v2 00/14] arch,mm: cleanup Kconfig entries for ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 01/14] arm: reword ARCH_FORCE_MAX_ORDER prompt and help text Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 02/14] arm64: drop ranges in definition of ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` Mike Rapoport [this message]
2023-03-24 13:48 ` [PATCH v2 03/14] arm64: reword ARCH_FORCE_MAX_ORDER prompt and help text Zi Yan
2023-03-24 5:22 ` [PATCH v2 04/14] csky: drop ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 05/14] ia64: don't allow users to override ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 06/14] m68k: reword ARCH_FORCE_MAX_ORDER prompt and help text Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 07/14] nios2: " Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 08/14] nios2: drop ranges for definition of ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 09/14] powerpc: reword ARCH_FORCE_MAX_ORDER prompt and help text Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 10/14] powerpc: drop ranges for definition of ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 11/14] sh: reword ARCH_FORCE_MAX_ORDER prompt and help text Mike Rapoport
2023-03-24 14:28 ` Zi Yan
2023-03-24 5:22 ` [PATCH v2 12/14] sh: drop ranges for definition of ARCH_FORCE_MAX_ORDER Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 13/14] sparc: reword ARCH_FORCE_MAX_ORDER prompt and help text Mike Rapoport
2023-03-24 5:22 ` [PATCH v2 14/14] xtensa: " Mike Rapoport
2023-03-24 14:30 ` [PATCH v2 00/14] arch,mm: cleanup Kconfig entries for ARCH_FORCE_MAX_ORDER Zi Yan
2023-03-24 16:48 ` Mike Rapoport
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