Depends on the workload, but yes.
>> 5. kmap
>> Persistent kmap sucks, and the global systemwide TLB flushes
>> scale as O(1/N^2) with the number of CPUs. Enlarging the kmap
>> area helps a little, but really we need to stop doing this to
>> ourselves. I will have a patch (hopefully within a week) to do
>> per-task kmap, based on the UKVA patch that Dave McCracken has
>> already implemented.
> O(1/N^2)? wouldn't that get progressively better as the number of cpu's
> grows without bound?
Cost of TLB flush on 1 cpu = 1. Number of CPUs = N. Cost of systemwide
TLB flush = N. Assuming we actually use those CPUs in a comparable way,
we do N times as many global tlbflushes per second with N cpus. This N^2.
Or that's my reckoning, anyway.
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