Flush cache lines in TCMalloc immediately before freeing memory to OS. - #1013
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When releasing memory to the OS in SystemAllocator::ReleasePages, flush all cache lines covering the page range using `clflushopt` (x86) or `dc civac` (arm) followed by a memory barrier (`sfence` / `dsb ish`). This evicts and writes back dirty cache lines before madvising pages away, preventing memory released back to the OS from using cache capacity/causing other still used cache lines to be evicted later. We use an 8K limit to avoid iterating over unbounded memory during deallocation. PiperOrigin-RevId: 981994488
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Flush cache lines in TCMalloc immediately before freeing memory to OS.
When releasing memory to the OS in SystemAllocator::ReleasePages, flush all cache lines covering the page range using
clflushopt(x86) ordc civac(arm) followed by a memory barrier (sfence/dsb ish).This evicts and writes back dirty cache lines before madvising pages away, preventing memory released back to the OS from using cache capacity/causing other still used cache lines to be evicted later.
We use an 8K limit to avoid iterating over unbounded memory during deallocation.