madvise() away metadata for drained CPUs. - #513
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When we drain (reclaim) inactive CPUs, we hand back all of the memory from its freelists into the transfer cache; however, the metadata keeping track of those freelists remains. When we have many drained CPUs in a row, and their metadata (which is contiguous) span an entire hugepage, we madvise() away that hugepage if the flag is on. This should save a little more RAM yet, on top of the existing draining. We only madvise() on hugepage boundaries, so that we do not tear hugepages and cause more TLB pressure. PiperOrigin-RevId: 960253910
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madvise() away metadata for drained CPUs.
When we drain (reclaim) inactive CPUs, we hand back all of the memory
from its freelists into the transfer cache; however, the metadata
keeping track of those freelists remains. When we have many drained CPUs
in a row, and their metadata (which is contiguous) span an entire
hugepage, we madvise() away that hugepage if the flag is on. This should
save a little more RAM yet, on top of the existing draining.
We only madvise() on hugepage boundaries, so that we do not tear
hugepages and cause more TLB pressure.