From: "Theo de Raadt" Subject: Re: [PATCH] amd64: import optimized memcmp from FreeBSD To: Christian Weisgerber Cc: tech@openbsd.org Date: Sat, 30 Nov 2024 10:45:02 -0700 Christian Weisgerber wrote: > Christian Schulte: > > > lately I thought about rewriting those functions to use simd, but never > > looked further into doing it, because I do not know if simd > > registers/instructions could be used there at all. Could they? Instead > > Presumably not in the kernel as we would have to save/restore > FPU/SIMD registers around those calls. Yes, this tradeoff is PROBABLY very poor, unless the copy is very large.