TODO: avoid overlap between legacy and HT rates.

Used to coordinate shared registers between HT threads or among events on a single PMU.

p4_threads - determines the number of logical processor threads in a die returns number of threads in p4 die (1 for non-HT processors). -p4_threads - determines the number of logical processor threads in a die returns number of threads in p4 die (

Represent Channel Width in HT Capabilities.