When the GC starts traversing the list of objects it fills the cache kicking out the previously cached things. This is a known performance problem in optimization. It's quite common. It also happens when having 2+ threads doing a lot of memory access.
And caches bring a whole cache line. So for every access, no matter how small, the minimum is 64 bytes are kicked out. Also the prefetch heuristics often bring more (e.g. next cache line).
There are cache control instructions but they are rarely used.
> Cache misses are currently a major factor in the cost of garbage
collection, and we expect them to dominate in the future.
Traditional garbage collection algorithms exhibit relatively
little temporal locality; each live object in the heap is likely to
be touched exactly once during each garbage collection. We
measure two techniques for dealing with this issue: prefetch-ongrey, and lazy sweeping. The first of these is new in this
context. Lazy sweeping has been in common use for a decade.
It was introduced as a mechanism for reducing paging and
pause times; we argue that it is also crucial for eliminating
cache misses during the sweep phase.
GC currently causes a lot of memory traffic, that is true. So don't touch the whole heap. Wow, that reference is old. It doesn't even use a generational collector. Hans is a bright guy and is up-to-date on current GCs; I kind of doubt that he'd agree with your use of his old paper to characterize today's GCs.
The counter to this is that with a moving, generational collector, the GC mainly touches memory in the young generation which then gets moved out of the young generation. This means that GC languages can have better locality since manually managed languages since all your new objects get allocated together better.
And caches bring a whole cache line. So for every access, no matter how small, the minimum is 64 bytes are kicked out. Also the prefetch heuristics often bring more (e.g. next cache line).
There are cache control instructions but they are rarely used.
[0] Reducing Garbage Collector Cache Misses (2000) (HP) https://www.hpl.hp.com/techreports/2000/HPL-2000-99.pdf
> Cache misses are currently a major factor in the cost of garbage collection, and we expect them to dominate in the future. Traditional garbage collection algorithms exhibit relatively little temporal locality; each live object in the heap is likely to be touched exactly once during each garbage collection. We measure two techniques for dealing with this issue: prefetch-ongrey, and lazy sweeping. The first of these is new in this context. Lazy sweeping has been in common use for a decade. It was introduced as a mechanism for reducing paging and pause times; we argue that it is also crucial for eliminating cache misses during the sweep phase.