RFR: 8293416: ZGC: Set mark bit with unconditional atomic ops [v3]

[Albert Mingkun Yang]

On Tue, 13 Sep 2022 03:12:28 GMT, hev <duke at openjdk.org> wrote:

>> src/hotspot/share/gc/z/zBitMap.inline.hpp line 67:
>> 
>>> 65:     inc_live = false;
>>> 66:     return false;
>>> 67:   }
>> 
>> The fast/slow paths are almost identical. I believe some numbers would be nice to justify the presence of the fast path.
>
> I think so. Atomic operations are more expensive than normal memory loads. This is why should split to fast and slow path, although they are almost Identical. The micro benchmark 2 shows it.

Thank you for the benchmark results; they are convincing, IMO.

-------------

PR: https://git.openjdk.org/jdk/pull/10182