From 6c22059925e5b975d971849071a8bb845c19fa63 Mon Sep 17 00:00:00 2001 From: lkcl Date: Fri, 25 Dec 2020 17:26:20 +0000 Subject: [PATCH] --- openpower/sv/overview.mdwn | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/openpower/sv/overview.mdwn b/openpower/sv/overview.mdwn index c2d3e21a7..8e736f024 100644 --- a/openpower/sv/overview.mdwn +++ b/openpower/sv/overview.mdwn @@ -11,11 +11,13 @@ SIMD, the primary method for easy parallelism of the past 30 years in Computer Architectures, is [known to be harmful](https://www.sigarch.org/simd-instructions-considered-harmful/). SIMD provides a seductive simplicity that is easy to implement in -hardware. Even with predication added, SIMD only becomes more and +hardware. With each doubling in width it promises increases in raw performance without the complexity of either multi-issue or out-of-order execution. + +Unfortunately, even with predication added, SIMD only becomes more and more problematic with each power of two SIMD width increase introduced through an ISA revision. The opcode proliferation, at O(N^6), inexorably spirals out of control in the ISA, detrimentally impacting the hardware, -the software and the compilers. +the software, the compilers and the testing and compliance. Cray-style variable-length Vectors on the other hand result in stunningly elegant and small loops, exceptionally high data throughput -- 2.30.2