Originally posted by TemplarGR
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Bisected: The Unfortunate Reason Linux 4.20 Is Running Slower
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Originally posted by ryao View PostIt looks like this should affect AMD hardware too:
https://arstechnica.com/gadgets/2018...t-performance/
My guess is is that Michael is testing AMD hardware that lacks the microcode update that gives stibp support. AMD’s website says that he needs to update his BIOS to get it:
https://www.amd.com/en/corporate/security-updates
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Originally posted by Michael View Post
All of my AMD systems were tested with their latest BIOS releases.
It looks like it is possible to install the amd64-microcode package on Ubuntu to get the fix. Debian suggests that just installing the package and rebooting would make it work:
I am not sure if it is that simple (i.e. does a boot script need to be enabled?), but if dmesg shows an update was done that was not there on a prior boot and /proc/cpuinfo starts showing stibp, you should have it.Last edited by ryao; 16 November 2018, 06:54 PM.
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Originally posted by Michael View Post
That's because according to Intel, the current mitigations already cover these new attack vectors.
https://www.theregister.co.uk/2018/1...down_variants/Last edited by ryao; 16 November 2018, 07:12 PM.
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Originally posted by Weasel View PostSee what I mean with idiots spreading bullshit on this forum about how it only affects Intel?
Until things have been properly scrutinized and re-evaluated, we will not know the extent to which AMD’s performance is affected by this patch. It could also be that many systems where it should be enabled by the logic in the kernel won’t have it enabled due to AMD discouraging the propagation of the microcode updates that provide the mitigations. The impact to the general public would be unfairly lessened by that.
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Originally posted by ryao View Post
Haswell introduced the INVPCID instruction which is used to re-gain some performance for some mitigations. Hence older processors than Haswell with the mitigations enabled should lose more performance than newer ones and I'd like to see the exact numbers. What that means: The performance implications should be even worse for these older systems.
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