RFR (M) #5 CR 8003985: Support @Contended annotation

[Doug Lea]

> On 01/11/2013 05:14 PM, Vitaly Davidovich wrote:

>> I still think it would be better to get line size from OS (or CPU)
>> rather than hardcoding a default - this seems orthogonal to the
>> prefetcher issue since the default you picked is probably going to be
>> either the same size or larger than what os/CPU would've reported.

In case it helps resolve this a bit:

The logistic problem is that we do not know a way to
reliably compute the effective cacheline length given
the possibility (and these days, likelihood) of adjacent
prefetching or other memory system quirks. And unreliable
detection is worse than no detection. So, in the near
term, the only course of action is to set this up using
reasonable defaults, and improve them over time.
Which is what Aleksey did.

-Doug