libproc
A system library provided by macOS for obtaining process information, including memory usage metrics such as phys_footprint.
Timeline (last 90 days)
On an Apple Silicon Mac, after moving a PyTorch tensor on the MPS device to the CPU via .to("cpu"), the process's phys_footprint immediately drops to near zero, but the tensor data remains fully in memory.
phys_footprint is a process-level memory metric that macOS exposes through libproc, and it is what the Memory column in Activity Monitor displays; it is an estimate of 'physical pages that are actually resident and counted toward system memory pressure', excluding the portion swapped out to swap, so under a unified memory architecture it falls rapidly when pages are marked as compressible or enter swap.
All Facts (2)
On an Apple Silicon Mac, after moving a PyTorch tensor on the MPS device to the CPU via .to("cpu"), the process's phys_footprint immediately drops to near zero, but the tensor data remains fully in memory.
50%Unverifiedphys_footprint is a process-level memory metric that macOS exposes through libproc, and it is what the Memory column in Activity Monitor displays; it is an estimate of 'physical pages that are actually resident and counted toward system memory pressure', excluding the portion swapped out to swap, so under a unified memory architecture it falls rapidly when pages are marked as compressible or enter swap.
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