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x86: Lower non-temporal copy threshold for Hygon

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Benchmarks on Hygon processors show that the default non-temporal
threshold is higher than ideal for large copy workloads.  As a result,
memcpy and memmove may continue to use the temporal copy path for
longer than is beneficial, increasing cache pollution and reducing
throughput for large copies.

Lower the copy non-temporal threshold to 3/8 of the shared cache size
per thread on Hygon.  This allows the non-temporal copy path to be
selected earlier while leaving the memset non-temporal threshold
unchanged.

Signed-off-by: xiejiamei <xiejiamei@hygon.cn>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
xiejiamei authored and Adhemerval Zanella committed 2026-05-20 17:22:12 -03:00
1 parent 994a437878
commit 213ffdfbba
1 file changed
+8
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sysdeps/x86/dl-cacheinfo.h
+8
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@@ -1255,6 +1255,14 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
if (tunable_size > minimum_non_temporal_threshold
&& tunable_size <= maximum_non_temporal_threshold)
non_temporal_threshold = tunable_size;
else if (cpu_features->basic.kind == arch_kind_hygon)
{
/* Hygon benefits from entering the non-temporal copy path earlier.
Use 3/8 of the shared cache size per thread for memcpy and
memmove. The memset threshold has already been initialized
above and is intentionally left unchanged. */
non_temporal_threshold = shared_per_thread * 3 / 8;
}
tunable_size = TUNABLE_GET (x86_memset_non_temporal_threshold, long int, NULL);
if (tunable_size > minimum_non_temporal_threshold