Usama Arif found that with the three patches to just probe BMI2 CPU support only once, it yield a 71% reduction in decompression time and a 18% reduction in compression time for a crypto_acomp benchmark.

Wow

[–] Deebster@infosec.pub 4 points 1 day ago (1 children)

Is it that slow outside of a VM? Either way, this seems like a very sensible patch.

[–] SteveTech@aussie.zone 4 points 19 hours ago* (last edited 15 hours ago)

It's only slightly faster. cpuid is a serialising instruction, which means all the instructions before it have to complete, removing any gains from pipelining and out of order execution. However for a VM this also triggers a VM exit, where the hypervisor takes over to modify the values for the guest.