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x86: Disable AVX Fast Unaligned Load on Hygon 1/2/3

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- Performance testing revealed significant memcpy performance degradation
  when bit_arch_AVX_Fast_Unaligned_Load is enabled on Hygon 3.
- Hygon confirmed AVX performance issues in certain memory functions.
- Glibc benchmarks show SSE outperforms AVX for
  memcpy/memmove/memset/strcmp/strcpy/strlen and so on.
- Hardware differences primarily in floating-point operations don't justify
  AVX usage for memory operations.

Reviewed-by: gaoxiang <gaoxiang@kylinos.cn>
Signed-off-by: litenglong <litenglong@kylinos.cn>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
litenglong
2025-10-17 09:45:41 +08:00
committed by H.J. Lu
parent b59799f14f
commit 00d406e77b
1 changed files with 6 additions and 0 deletions
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6
sysdeps/x86/cpu-features.c
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@@ -1123,6 +1123,12 @@ disable_tsx:
hardware. */ hardware. */
cpu_features->preferred[index_arch_Avoid_Non_Temporal_Memset] cpu_features->preferred[index_arch_Avoid_Non_Temporal_Memset]
&= ~bit_arch_Avoid_Non_Temporal_Memset; &= ~bit_arch_Avoid_Non_Temporal_Memset;
if (model < 0x4)
{
/* Unaligned AVX loads are slower. */
cpu_features->preferred[index_arch_AVX_Fast_Unaligned_Load]
&= ~bit_arch_AVX_Fast_Unaligned_Load;
}
} }
else else
{ {