To use HVO, make sure that the kernel is booted with pseudo-NMI enabled by "irqchip.gicv3_pseudo_nmi=1", as well as "hugetlb_free_vmemmap=on" unless HVO is enabled by default. Note that HVO checks the pseudo-NMI capability and is disabled at runtime if that turns out not supported. Successfully enabling HVO should have the following: # dmesg | grep NMI GICv3: Pseudo-NMIs enabled using ... # sysctl vm.hugetlb_optimize_vmemmap vm.hugetlb_optimize_vmemmap = 1 For comparison purposes, the whole series was measured against this patch only, to show the overhead from pausing remote CPUs: HugeTLB operations This patch only The whole series Change Alloc 600 1GB 0m3.526s 0m3.649s +4% Free 600 1GB 0m0.880s 0m0.917s +4% Demote 600 1GB to 307200 2MB 0m1.575s 0m3.640s +231% Free 307200 2MB 0m0.946s 0m2.921s +309% Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> --- arch/arm64/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index fd9df6dcc593..e93745f819d9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -109,6 +109,7 @@ config ARM64 select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT select ARCH_WANT_FRAME_POINTERS select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36) + select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP select ARCH_WANT_LD_ORPHAN_WARN select ARCH_WANTS_EXECMEM_LATE if EXECMEM select ARCH_WANTS_NO_INSTR -- 2.47.0.277.g8800431eea-goog
