A more general possible meltdown/spectre countermeasure
Eric McCorkle
eric at metricspace.net
Fri Jan 5 12:30:51 UTC 2018
On 01/05/2018 03:15, Dag-Erling Smørgrav wrote:
> Eric McCorkle <eric at metricspace.net> writes:
>> The obvious downside is that you take a performance hit storing things
>> in non-cacheable locations, especially if you plan on doing heavy
>> computation in that memory (say, encryption/decryption). However, this
>> is almost certainly going to be less than the projected 30-50%
>> performance hit from other mitigations.
>
> Where did you get those numbers? Because the worst documented case for
> KPTI is ~20% for I/O-intensive workloads, and PCID is likely to bring
> this down to single digits if used correctly. The KAISER paper claims a
> slowdown of < 1%, but that may have been the result of undisclosed
> features of the specific CPU they tested on.
Those were numbers being thrown around. I'm not putting a lot of stake
in them.
More information about the freebsd-security
mailing list