Hi,
Note that not taking this bit for the age field would open the door to
reducing the alignment of the JavaThread*. It's the fact that there was
already an unclaimed bit there (in the 64-bit version) that made the age
size increase seem more reasonable.
However, I'd propose not changing that, either, at least for the 64-bit
version, so that when someone finally claims "the bit" it doesn't need
to be undone. For the 32-bit version, it's less clear cut, but I'd
still lean toward leaving it as is.
Tom
On 2/13/2015 11:37 AM, Bengt Rutisson wrote:
Hi,
On 2015-02-13 16:37, Tom Benson wrote:
Hi,
Based on comments here and elsewhere on possible future uses for this
unused bit (in the 64-bit version), I'm more inclined to close both
6764713 and 6719225 with no change. With a comment along the lines
of "evolution of the JVM since the time the age field was reduced has
revealed potentially more valuable uses of the bit."
This sounds like a good approach in my view. I think we can leave the
age at 4 bits. In my view the main issue with the aging is that our
heuristics for adjusting the tenuring threshold are not always
reliable. Sometimes the threshold gets stuck at the max value etc. I
prefer to close these bug reports as suggested above and if we want to
improve the tenuring we should work on the heuristics instead.
Thanks for digging these bug reports up, Tom! We should probably have
brought them up for discussion and closing them a long time ago.
Thanks,
Bengt
However, if there are supporters of a larger MaxTenuringThreshold
lurking, I'd like to hear their point of view as well.
Thanks,
Tom
