[Issue 19617] [REG 2.085a] Much slower GC compared to 2.084

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19617

Rainer Schuetze <r.sagitario at gmx.de> changed:

           What    |Removed                     |Added
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                 CC|                            |r.sagitario at gmx.de

--- Comment #2 from Rainer Schuetze <r.sagitario at gmx.de> ---
There is little difference on my system between 2.083 and git HEAD, maybe 110
µs and 120 µs, respectively. These number are way too small for a benchmark as
every unrelated detail can make a big difference. If I make the text longer so
that the time is a about 1ms (still very small), the absolute difference is
about the same if at all noticable in the noise.

The most likely related change in the GC is that intermediate allocation sizes
are now supported, too (these were power of 2 only so far). This can lead to
less memory being used for the same allocations (up to about 30%), but it also
changes when collections are run. Appending to arrays might also reallocate a
bit more often.

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