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Atomic Virus

Overview

The atomic_virus is designed to overwhelm the L2 Cache Arbiters. It hammers memory with Atomic operations using a wide stride to force continuous "Read-Modify-Write" cycles.

Execution Mechanics

The kernel allocates roughly 60% of the available VRAM to ensure the working set spills out of the ultra-fast L1 cache and forces continuous trips to L2.

  • Threads perform an atomicAdd on wide-strided memory addresses.
  • This forces the hardware to lock the cache line, read the value, update it, write it back, and unlock it.
  • By doing this concurrently across millions of threads, the internal fabric handling cache coherency is pushed to its absolute limit.

Target Subsystems

  • Primary Target: L2 Cache Arbiters and Render Output Units (ROPs).
  • Secondary Target: Cache coherency fabric.

Failure Symptoms

Critical Failures

  • Erratic Performance: Severe drops in MAPS (Million Atomic Operations Per Second) indicate the arbiters are thermal-throttling or dropping requests.
  • Application Crashes: Cache locking mechanisms fail, causing a segmentation fault or unhandled memory exception.