commit bef2d6da4ea5d67647d310a3cca5ede09385cf05
author Jieqiang Wang <jieqiang.wang@arm.com> Tue Jul 04 12:05:33 2023 +0800
committer Damjan Marion <dmarion@0xa5.net> Sun Oct 01 21:11:32 2023 +0000
tree 0da214f4f80c74a7efd66f5cb31ffb8c03b2bef3
parent e7f34c93b1c928855f88896c5bdd2bc539ee77ae

build: modify N_PREFETCH on Arm N2 to achieve best perf

From GCC 12, march=armv9-a option is supported, which includes the sve
and crc options needed. Furthermore, VPP L3Fwd benchmark results on N2
based servers show that N_PREFETCH set to 6 gives the best performance.

Type: feature

Signed-off-by: Lijian Zhang <Lijian.Zhang@arm.com>
Signed-off-by: Jieqiang Wang <jieqiang.wang@arm.com>
Change-Id: I9c4fcad84d4db1189d956dabab22b26d020fbfd6

src/cmake/cpu.cmake

diff --git a/src/cmake/cpu.cmake b/src/cmake/cpu.cmake
index f683b62..18a1210 100644
--- a/src/cmake/cpu.cmake
+++ b/src/cmake/cpu.cmake
@@ -194,10 +194,9 @@
     N_PREFETCHES 6
     CACHE_PREFETCH_BYTES 64
   )
-
   add_vpp_march_variant(neoversen2
-    FLAGS -march=armv8.6-a+crc+crypto+sve2 -mtune=neoverse-n2
-    N_PREFETCHES 8
+    FLAGS -march=armv9-a+crypto -mtune=neoverse-n2
+    N_PREFETCHES 6
     CACHE_PREFETCH_BYTES 64
     OFF
   )