RFR: Use allocation counter instead of timestamp to track region's age

[Aleksey Shipilev]

On 08/02/2017 08:25 PM, Zhengyu Gu wrote:
>> *) Excess whitespace. Also, comment should mention they are also set on allocation paths.
>>
>>   60   // Seq numbers are used for generational and Least Recently Used heuristics.
>>   61   // They are set when a region is discarded
>>   62   uint64_t  _first_alloc_seq_num;
>>   63   uint64_t  _last_alloc_seq_num;
>>
> Fixed

Not fixed in webrev.01? At least the comment should be updated.

New:

*) I guess 20 is too wide? We don't expect to survive 10^20 allocations, don't we? Suggesting e.g.
15. (That's about 15 PB with non-TLAB allocs).

 152   st->print("|FTS " SIZE_FORMAT_W(20), first_alloc_seq_num());
 153   st->print("|LTS " SIZE_FORMAT_W(20), last_alloc_seq_num());

Otherwise good. No need to rerun the tests for these cosmetics.

Thanks,
-Aleksey