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Running Fusion on a Machine with Multiple CPUs

Fusion can be configured to use a maximum number of CPUs on a machine with the following command:

/opt/google/bin/geselectassetroot --assetroot /my/assetroot --numcpus X This number will show up as the maxjobs entry within getop output and corresponds to how many concurrent jobs Fusion may spawn at any one time. Note that the value for –numcpus should be equal to, or less than, the number of physical CPU cores on the machine.

Each task within Fusion is configured to use 1 CPU by default. Changing the maximum number of CPUs using the above command will not affect the number of CPUs assigned to each individual task. Some tasks in Fusion are capable of multithreaded support including:

  • gepackgen (imagery and terrain projects)
  • gemaptilegen (2D vector-based map tiles)
  • gecombineterrain (3D databases)

These tasks may be multithreaded by enabling task rules within Fusion. Implementation of task rules is described in more detail in Configure Fusion performance.

The ImageryPacketLevel.taskrule, TerrainPacketLevel.taskrule, MapLayerLevel.taskrule, and CombinedTerrain.taskrule task rules enable multiple CPUs to work on each individual task. For example, configuring a minNumCPUs and maxNumCPUs of two for the ImageryPacketLevel.taskrule means that up to four gepackgen processes may run on Fusion when eight CPU cores are allocated.

As a best practice, ImageryPacketLevel.taskrule, TerrainPacketLevel.taskrule and MapLayerLevel.taskrule should be configured such that multiple gepackgen and gemaptilegen processes can run concurrently.

Since gecombineterrain is CPU-intensive and can be an operational bottleneck, more CPUs should be assigned to that task to expedite processing. So on a machine with eight CPU cores available for Fusion processing:

  1. Set /opt/google/bin/geselectassetroot --assetroot /my/assetroot --numcpus=7. It’s recommended to set the maximum number of CPUs allocated to Fusion to (N-1), such that one CPU core is reserved for system operations.

  2. Set minNumCPU=2 and maxNumCPU=2 in ImageryPacketLevel.taskrule for imagery projects (three concurrent gepackgen tasks possible).**

  3. Set minNumCPU=3 and maxNumCPU=4 in TerrainPacketLevel.taskrule for terrain projects (two concurrent gepackgen tasks possible)**

  4. Set minNumCPU=3 and maxNumCPU=4 in MapLayerLevel.taskrule (two concurrent gemaptilegen jobs possible).

  5. Set minNumCPU=7 and maxNumCPU=7 in CombinedTerrain.taskrule (one gecombineterrain task)


    Fusion will use up to 200% CPU processing for imagery projects per gepackgen process, and up to 400% CPU processing for terrain projects. There is fundamentally a balance between assigning sufficient numbers of CPUs to each individual process for gepackgen while still enabling multiple concurrent gepackgen processes for parallel processing.

    All other tasks in Fusion will continue to operate with min/max one CPU.