diff options
Diffstat (limited to 'AArch64-Update-A64FX-memset-not-to-degrade-at-16KB.patch')
| -rw-r--r-- | AArch64-Update-A64FX-memset-not-to-degrade-at-16KB.patch | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/AArch64-Update-A64FX-memset-not-to-degrade-at-16KB.patch b/AArch64-Update-A64FX-memset-not-to-degrade-at-16KB.patch new file mode 100644 index 0000000..f7ce84d --- /dev/null +++ b/AArch64-Update-A64FX-memset-not-to-degrade-at-16KB.patch @@ -0,0 +1,39 @@ +From 23777232c23f80809613bdfa329f63aadf992922 Mon Sep 17 00:00:00 2001 +From: Naohiro Tamura via Libc-alpha <libc-alpha@sourceware.org> +Date: Fri, 27 Aug 2021 05:03:04 +0000 +Subject: [PATCH] AArch64: Update A64FX memset not to degrade at 16KB + +This patch updates unroll8 code so as not to degrade at the peak +performance 16KB for both FX1000 and FX700. + +Inserted 2 instructions at the beginning of the unroll8 loop, +cmp and branch, are a workaround that is found heuristically. + +Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com> +--- + sysdeps/aarch64/multiarch/memset_a64fx.S | 9 ++++++++- + 1 file changed, 8 insertions(+), 1 deletion(-) + +diff --git a/sysdeps/aarch64/multiarch/memset_a64fx.S b/sysdeps/aarch64/multiarch/memset_a64fx.S +index 7bf759b..f7dfdaa 100644 +--- a/sysdeps/aarch64/multiarch/memset_a64fx.S ++++ b/sysdeps/aarch64/multiarch/memset_a64fx.S +@@ -96,7 +96,14 @@ L(vl_agnostic): // VL Agnostic + L(unroll8): + sub count, count, tmp1 + .p2align 4 +-1: st1b_unroll 0, 7 ++ // The 2 instructions at the beginning of the following loop, ++ // cmp and branch, are a workaround so as not to degrade at ++ // the peak performance 16KB. ++ // It is found heuristically and the branch condition, b.ne, ++ // is chosen intentionally never to jump. ++1: cmp xzr, xzr ++ b.ne 1b ++ st1b_unroll 0, 7 + add dst, dst, tmp1 + subs count, count, tmp1 + b.hi 1b +-- +1.8.3.1 + |