A more general possible meltdown/spectre countermeasure

[Dag-Erling Smørgrav]

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.

DES
-- 
Dag-Erling Smørgrav - des at des.no