From 6d92ba34b7432b8df938f48d69d0fd60d9c35061 Mon Sep 17 00:00:00 2001 From: Martin Kronbichler Date: Mon, 14 Aug 2023 17:30:20 +0200 Subject: [PATCH] Add changelog --- doc/news/changes/minor/20230814Kronbichler | 12 ++++++++++++ 1 file changed, 12 insertions(+) create mode 100644 doc/news/changes/minor/20230814Kronbichler diff --git a/doc/news/changes/minor/20230814Kronbichler b/doc/news/changes/minor/20230814Kronbichler new file mode 100644 index 0000000000..e1499eff0a --- /dev/null +++ b/doc/news/changes/minor/20230814Kronbichler @@ -0,0 +1,12 @@ +Improved: deal.II now has a flag DEAL_II_USE_VECTORIZATION_GATHER to control +the use of gather/scatter instructions on the x86 architecture. On a wide +range of Intel hardware with microcode mitigation for the Intel Gather Data +Speculation (GDS, aka Downfall) side channel vulnerability, in particular, +server processors of the Broadwell, Skylake, Cascade Lake, and Ice Lake +families released between 2015 and 2021, these instructions can be much slower +than scalar loads. While the default behavior of deal.II is to aggressively +enable these instructions in the intrinsics-class VectorizedArray, the new +variable can be used to disable their use if deemed to give better +performance. +
+(Martin Kronbichler, Matthias Maier, 2023/08/14) -- 2.39.5