* Kalesh Singh kaleshsingh@google.com wrote:
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@google.com Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: H. Peter Anvin hpa@zytor.com
Nice!
Assuming it's all correct code:
Acked-by: Ingo Molnar mingo@kernel.org
Thanks,
Ingo