[PATCH v4 5/5] x86: mremap speedup - Enable HAVE_MOVE_PUD
Kalesh Singh
kaleshsingh at google.com
Tue Oct 13 20:53:10 EDT 2020
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 at google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Borislav Petkov <bp at alien8.de>
Cc: H. Peter Anvin <hpa at zytor.com>
---
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
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