Hi Everyone, I was performing some benchmarking today. On a Skylake Core-i5-6400 machine, and in the past (May 30, 2020), I would see these performance numbers:
RDRAND: 67 MB/s, ~38 cpb RDSEED: 24 MB/s, ~105 cpb I ran the same benchmarks today (January 2 2020) and the benchmark program reported: RDRAND: 7 MB/s, ~360 cpb RDSEED: 7 MB/s, ~360 cpb I checked out the same code from the past (May 30, 2020) and the numbers stayed the same: RDRAND: 7 MB/s, ~360 cpb RDSEED: 7 MB/s, ~360 cpb SSE2, SSE4, AVX, AES-NI, SHA-NI, etc are OK. The hardware is the same, but the OS was upgraded from Fedora 32 to Fedora 33. The kernel and possibly intel-microcode have changed between May 2020 and January 2021. I'm aware of this problem with AMD's RDRAND and RDSEED, but it doesn't affect Intel machines: https://bugzilla.kernel.org/show_bug.cgi?id=85911 (so there should not be any remediations in place). My question is, is anyone aware of what may be responsible for the performance loss? Thanks in advance, Jeff
