CPU performance - disable bug mitigations
sendmailtogoran at gmail.com
Tue Nov 20 16:05:08 UTC 2018
I have some servers with AMD Opteron 6276 CPUs and doing some number
crunching on these.
I installed Ubuntu 16.04 and was pretty much satisfied (never did an
update - running local only). Some days ago I installed 18.04 and got
a performance penalty of 33%.
My guess is, that it has something to do with Spectre. So I did a
# grep . /sys/devices/system/cpu/vulnerabilities/*
Speculative Store Bypass disabled via prctl and seccomp
AMD retpoline, IBPB
How can I disable these mitigations without restart (without boot
command line)? I just found some examples for Red Hat which are not
working for Ubuntu.
Further I read these pages:
I would like to disable all mitigations related to any of these hardware-bugs.
After all I got the harshest penalty when I switched back to 16.04.5
(fresh new install) and could not get my performance back. My old
16.04 is lost so no way back.
How to get back my performance?
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