- set_gpu_blocking_sync(): every device is put in
cudaDeviceScheduleBlockingSync before its context exists, so a host thread
waiting on the GPU sleeps instead of spinning on a core. On a 16M rotation
run a fifth of all CPU time was that spinning; wall time unchanged within
noise. Called first thing in rugnux.
- enable_gpu_numa_binding(): from then on pin_gpu() (and the new
pin_gpu(dev), used by the first-pass spot workers that take a card by
index) also keeps the thread on the CPUs of the NUMA node the card hangs
off. The node and its CPUs come from /sys (no libnuma), intersected with
the process's own mask; Linux only, and nothing happens on a machine with a
single node. rugnux turns it on; the broker does not.
- A thread inherits its creator's affinity, so the shared ParallelFor pool
would run every later pass on one socket if a pinned worker created it:
its threads now reset to the mask the process started with
(common/ThreadAffinity).
Byte-identical output. The NUMA part is a no-op on the single-node test box
and still has to be measured on a two-socket machine.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D1G8gJVAy6gp1K5Dz3NE5C
