On 07/11/2022 06:58, Michael Paquier wrote:
#if defined(_WIN64)
static __forceinline void
spin_delay(void)
{
+#ifdef _M_ARM64
+ /*
+ * arm64 way of hinting processor for spin loops optimisations
+ * ref:
https://community.arm.com/support-forums/f/infrastructure-solutions-forum/48654/ssetoneon-faq
+ */
+ __isb(_ARM64_BARRIER_SY);
+#else
_mm_pause();
+#endif
}
#else
static __forceinline void
I think we should just apply this, there seems very little risk of making
anything worse, given the gating to _WIN64 && _M_ARM64.
Seems so. Hmm, where does _ARM64_BARRIER_SY come from? Perhaps it
would be better to have a comment referring to it from a different
place than the forums of arm, like some actual docs?
_ARM64_BARRIER_SY is defined in Microsoft Arm64 intrinsic documentation
-
https://learn.microsoft.com/en-us/cpp/intrinsics/arm64-intrinsics?view=msvc-170#BarrierRestrictions
I couldn't find something more official for the sse2neon library part.
--
Niyas
