RFR 8231264: Disable biased-locking and deprecate all flags related to biased-locking

[David Holmes]

On 27/11/2019 11:55 pm, Andrew Haley wrote:
> On 11/27/19 1:24 AM, John Rose wrote:
>> For now, I will be glad to see us prove (by experience) that BL is no longer
>> needed on today’s workloads and hardware, and can be deleted.  Current
>> evidence indicates this is possible. Barring new evidence, we need to clear
>> the decks here for future work.
> 
> What evidence is that? We've already heard that one of the benchmarks
> quoted (SPECjbb2015) was specifically written so that locks are more
> or less contended, so that locks get out of their biased state.
> According to the author of the benchmark, "therefore, arguing that
> biased locking is not needed because SPECjbb2015 does not show the
> benefit of having it enabled -- is circular."

SPECjbb2015 was used as supporting evidence that a modern benchmark that 
people like to measure and report is not impacted by this change. As I 
now know there is a good reason for that. But if SPECjbb2015 is somehow 
supposed to be representative of some class of real applications then 
this also bodes well for those applications.

David