crypto/tls: mention cpu frequency scaling in "why does using GOMAXPROCS > 1 sometimes make my program slower?"

[gopherbot]

by giantchen:

When I was benchmarking TLS handshaking with http://play.golang.org/p/WZlt7mI4WN , I
noticed that using GOMAXPROCS > 1 does make my program significantly slower (1.5x ~
2x). And I found the reason to be CPU frequency scaling, because no threads run hot
enough to stimulate CPU cores.

May be worth mention that in the FAQ.

[bradfitz]

Comment 1:

Frequency scaling (if it was your problem) would also affect the GOMAXPROCS == 1 case,
so it doesn't seem worth mentioning there in the FAQ.  It's also possibly misleading.

Status changed to WontFix.