NOTE: Currently there are a couple of assumptions:

1. Homogenous cluster set up
2. model gradients transfer is the same as the model size saved in ckpts (model_factory)
3. Parameter Server / Worker frameworks (All-reduce not yet implemented)
4. Synchronize SGD

Execution

1. Before the exection, what's needed?

   1. Infrastructure details Define the hierarchy and resource capacity of the infrastructure in cluster_spec.csv. For example, we have a cluster with 4 racks (switches). Under each rack (switch), there are 32 nodes. And each node has 128 CPU cores, 256 GB memory, and 8 GPUs. Then cluster_spec.csv will look like this:

      num_switch,num_node_p_switch,num_gpu_p_node,num_cpu_p_node,mem_p_node
      4,32,8,128,256
      

   2. Job trace The job trace to simulate. For each job, the simulator needs the following information:
      • job_id: for tracking
      • num_gpu: gpu requirement
      • submit_time: when the job is submitted. The simulator is event-based and discrete-time. Therefore, the time value starts from 0, and in second-scale.
      • iterations: the number of iterations to training. Used by Network costs calculation when in data parallel jobs.
      • model_name: what's the model in that job. This is used to estimate GPU memory usage, and network costs.
      • duration: how long this job will run. This information is used to generate job completion event by the simulator.
      • interval: job submission interval from this job to the next job

2. How to run the simulator? A simple example of the execution commend should be:

   python execute.py
   

   Inside the execute file The following options are necessary:

   • --cluster_spec: infrastructure spec file
   • --trace_file: job trace
   • --scheme: placement scheme
   • --schedule: scheduler

   Optional inputs:

   • --print: print debug information
   • --log_path: the output path of the log (cluster, job). The default will be time-stamp folder under current path

3. What are the placement and scheduling algorithms provided? Placement:

   • yarn: get GPUs from the same server nodes under the same switch

   Scheduling

   • fifo
   • sjf: Smallest-job-first, in terms of GPU requirement
   • TODO BELOW
   • lpjf: longest pending job first
   • shorest: shorestest remaining time job first
   • shorest-gpu: shortest-remaining-gputime job first
   • dlas: discretized LAS (just time-based) In jobs.py, you need to specify num_queue and queue_limit for MLFQ (also for dlas-gpu, and gittins)

     # Example1: there are two queues, and the threshold for Q1 is 3600 seconds
     self.queue_limit = [3600]
     
     # Example2: there are four queues, and the threshold for queues is 3600, 7200, 18000 seconds
     self.queue_limit = [3600, 7200, 18000]

   • dlas-gpu: discretized LAS (gpu-time-based)
   • gittins: discretized Gittins Index (gpu-time-based)

4. What's the output? Based on the --log_path, all the output files are in that folder (e.g., result-20190210-12-20-37 including:

   1. cluster.csv: cluster-level resource utilization info at each event point
   2. jobs.csv: the job execution information
   3. cpu.csv, gpu.csv, memory.csv, network.csv: those are the utilization details of each resource unit at event points. However, those logs are not accurate under some combinations of placement and scheduler. When count is chosen, those files are not generated.

   The output logs are defined in log.py; You can modify that file to adjust the output information.

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