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 19x improvement in performance on arm64. (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 arm64. All times are in nanoseconds. Control HAVE_MOVE_PUD 1247761 74271 1219896 46771 1094792 59687 1227760 48385 1043698 76666 1101771 50365 1159896 52500 1143594 75261 1025833 61354 1078125 48697 1134312.6 59395.7 <-- Mean time in nanoseconds A 1GB mremap completion time drops from ~1.1 milliseconds to ~59 microseconds on arm64. (~19x speed up). Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx> --- arch/arm64/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 844d089668e3..4d521f0a5863 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -122,6 +122,7 @@ config ARM64 select HANDLE_DOMAIN_IRQ select HARDIRQS_SW_RESEND select HAVE_MOVE_PMD + select HAVE_MOVE_PUD select HAVE_PCI select HAVE_ACPI_APEI if (ACPI && EFI) select HAVE_ALIGNED_STRUCT_PAGE if SLUB -- 2.28.0.709.gb0816b6eb0-goog
