Re: [RFC 2/3] arm64/hugetlb: Enable HUGETLB_PAGE_SIZE_VARIABLE
On 2/5/21 1:50 PM, David Hildenbrand wrote: > On 04.02.21 08:01, Anshuman Khandual wrote: >> MAX_ORDER which invariably depends on FORCE_MAX_ZONEORDER can be a variable >> for a given page size, depending on whether TRANSPARENT_HUGEPAGE is enabled >> or not. In certain page size and THP combinations HUGETLB_PAGE_ORDER can be >> greater than MAX_ORDER, making it unusable as pageblock_order. > > Just so I understand correctly, this does not imply that we have THP that > exceed the pageblock size / MAX_ORDER size, correct? Correct. MAX_ORDER gets incremented when THP is enabled. config FORCE_MAX_ZONEORDER int default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE) default "12" if (ARM64_16K_PAGES && TRANSPARENT_HUGEPAGE) default "11"
Re: [RFC 2/3] arm64/hugetlb: Enable HUGETLB_PAGE_SIZE_VARIABLE
On 04.02.21 08:01, Anshuman Khandual wrote: MAX_ORDER which invariably depends on FORCE_MAX_ZONEORDER can be a variable for a given page size, depending on whether TRANSPARENT_HUGEPAGE is enabled or not. In certain page size and THP combinations HUGETLB_PAGE_ORDER can be greater than MAX_ORDER, making it unusable as pageblock_order. Just so I understand correctly, this does not imply that we have THP that exceed the pageblock size / MAX_ORDER size, correct? This enables HUGETLB_PAGE_SIZE_VARIABLE making pageblock_order a variable rather than the compile time constant HUGETLB_PAGE_ORDER which could break MAX_ORDER rule for certain configurations. Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-ker...@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual --- arch/arm64/Kconfig | 4 1 file changed, 4 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 175914f2f340..c4acf8230f20 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1918,6 +1918,10 @@ config ARCH_ENABLE_THP_MIGRATION def_bool y depends on TRANSPARENT_HUGEPAGE +config HUGETLB_PAGE_SIZE_VARIABLE + def_bool y + depends on HUGETLB_PAGE + menu "Power management options" source "kernel/power/Kconfig" -- Thanks, David / dhildenb
[RFC 2/3] arm64/hugetlb: Enable HUGETLB_PAGE_SIZE_VARIABLE
MAX_ORDER which invariably depends on FORCE_MAX_ZONEORDER can be a variable for a given page size, depending on whether TRANSPARENT_HUGEPAGE is enabled or not. In certain page size and THP combinations HUGETLB_PAGE_ORDER can be greater than MAX_ORDER, making it unusable as pageblock_order. This enables HUGETLB_PAGE_SIZE_VARIABLE making pageblock_order a variable rather than the compile time constant HUGETLB_PAGE_ORDER which could break MAX_ORDER rule for certain configurations. Cc: Catalin Marinas Cc: Will Deacon Cc: linux-arm-ker...@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual --- arch/arm64/Kconfig | 4 1 file changed, 4 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 175914f2f340..c4acf8230f20 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1918,6 +1918,10 @@ config ARCH_ENABLE_THP_MIGRATION def_bool y depends on TRANSPARENT_HUGEPAGE +config HUGETLB_PAGE_SIZE_VARIABLE + def_bool y + depends on HUGETLB_PAGE + menu "Power management options" source "kernel/power/Kconfig" -- 2.20.1
