corekiln

Native macOS · C and Metal · no dependencies

Hold a Mac at full load, honestly.

Corekiln keeps every logical CPU busy, a Metal compute queue saturated, or both, until you stop it. macOS keeps control of scheduling, frequency, throttling and shutdown — Corekiln does not disable or bypass any of it.

Build and run View source

Workers

Metal command slots

1
2
3

Thermal pressure

nominal
cpu_work_units
0
gpu_dispatches
0
elapsed
0.0s
peak
nominal


      

        

          
          
          
        

        
        
        
        
      


      

        
        bin/corekiln --both --duration 20 --status 5
        
      

    

    

      A model of a run, not a measurement — nothing on this page loads your machine.
      The output lines, the flag rules and the counter names are the real ones.
    

  


  
  

    

      

        
The counters

        
Two numbers, and what they are not

        

          Corekiln reports progress, not performance. Both counters exist to show
          that the selected engines are still making forward progress — nothing more.
        

      

      

        

          cpu_work_units
          
Completed arithmetic batches

          
One work unit is one completed 4,096-iteration arithmetic batch on one worker thread.

          
Not a utilisation percentage. Not a benchmark score. Not comparable between machines.

        

        

          gpu_dispatches
          
Completed command buffers

          
One dispatch is one Metal command buffer that ran to completion. Three slots stay in flight at a time.

          
Not frames, not FLOPs, and not a measure of how much of the GPU you got.

        

      

      

        

          Activity Monitor reports CPU usage per logical CPU, so a process
          occupying eight of them can read near 800 percent. Frequency may fall once
          macOS throttles, even while Corekiln keeps every worker runnable — the
          work-unit rate drops and the load does not.
        

        

          Without --status the output is just the startup
          line and corekiln: stopped.
        

      

    

  


  
  

    

      

        
Thermal

        
A state macOS reports, not a temperature

        

          Corekiln passes through the qualitative thermal-pressure state from a
          public API. There is no sensor reading here, no degrees, and no elevated
          privilege anywhere in the program.
        

      

      

        
nominal
No thermal pressure reported.

        
fair
Mild pressure. The system has begun to respond.

        
serious
Noticeable measures in effect. The final report records when this was first reached.

        
critical
The system is taking aggressive measures.

        
unknown
Used when no known state is available.

      

      

        

          The final report carries peak_thermal and
          serious_at — the moment pressure first reached
          serious, or not_reached. That pair is the useful
          artefact of a soak: not how fast the machine went, but how long it held
          before the system started defending itself.
        

      

    

  


  
  

    

      

        
Limits

        
What it deliberately does not do

      

      

        
Never bypasses macOS
Scheduling, frequency scaling, thermal throttling and emergency shutdown all stay with the operating system. Corekiln only keeps threads runnable and command buffers queued.

        
No elevated privileges
Public APIs only. No sudo, no kexts, no entitlements to grant.

        
Nothing left behind
No daemon, no launch agent, no login item, no restart mechanism. When the process stops, it is gone.

        
Mode flags are exclusive
--cpu, --gpu and --both cannot be combined, and --workers is rejected with --gpu rather than silently ignored.

        
No package manager
The wrapper compiles the executable with Clang against Foundation and Metal, and reuses it until a source file or header changes.

      


      

        
Caution

        

          Corekiln intentionally creates sustained maximum demand. Combined mode
          produces substantially more heat and power draw than CPU-only. Expect higher
          temperature, higher power consumption, fan activity where applicable, lower
          battery life, and possible interface sluggishness.
        

        

          Save important work, connect appropriate power, keep vents unobstructed, and
          stop the process if the machine behaves unexpectedly.
        

      


      

        
1,239lines of C and Objective-C

        
4,096iterations per CPU work unit

        
3Metal command slots in flight

        
0dependencies, daemons or privileges

      

    

  


  
  

    

      

        
Run it

        
One command, no build system

        

          Needs macOS and the Xcode Command Line Tools
          (xcode-select --install). The first run compiles the
          native executable to .build/corekiln; later runs
          reuse it.
        

      

      

        

          
Start here

          
Clone and run

          
With no options it loads every active logical CPU and the GPU until you press Ctrl-C.

          
git clone https://github.com/romankhadka/corekiln.git
cd corekiln
bin/corekiln

        


        

          
Examples

          
Narrower runs

          
# two logical CPUs, until interrupted
bin/corekiln --cpu --workers 2

# GPU only, ten seconds
bin/corekiln --gpu --duration 10

# both, with progress every two seconds
bin/corekiln --both --duration 10 --status 2

        


        

          
Verify

          
The test suite

          
Black-box: it compiles the executable with strict warnings and exercises argument validation, every resource mode, timed shutdown, interrupt handling, the wrapper build, and real Metal command completion.

          
ruby test/corekiln_test.rb

        


        

          
Watch

          
From outside

          
Activity Monitor shows per-logical-CPU usage, and its GPU History window shows GPU load. macOS still reserves capacity for the display and other applications, so neither will read as a clean 100 percent.