HAVE_MOVE_PUD enables remapping pages at the PUD level if both the source and destination addresses are PUD-aligned. With HAVE_MOVE_PUD enabled it can be inferred that there is approximately a 13x improvement in performance on x86. (See data below). ------- Test Results --------- The following results were obtained using a 5.4 kernel, by remapping a PUD-aligned, 1GB sized region to a PUD-aligned destination. The results from 10 iterations of the test are given below: Total mremap times for 1GB data on x86. All times are in nanoseconds. Control HAVE_MOVE_PUD 180394 15089 235728 14056 238931 25741 187330 13838 241742 14187 177925 14778 182758 14728 160872 14418 205813 15107 245722 13998 205721.5 15594 <-- Mean time in nanoseconds A 1GB mremap completion time drops from ~205 microseconds to ~15 microseconds on x86. (~13x speed up). Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> --- Changes in v4: - Add Kirill's Acked-by. arch/x86/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 835d93006bd6..e199760d54fc 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -198,6 +198,7 @@ config X86 select HAVE_MIXED_BREAKPOINTS_REGS select HAVE_MOD_ARCH_SPECIFIC select HAVE_MOVE_PMD + select HAVE_MOVE_PUD select HAVE_NMI select HAVE_OPROFILE select HAVE_OPTPROBES -- 2.28.0.1011.ga647a8990f-goog
