Appendix – SNAP Memory Consumption

This appendix explains how SNAP consumes memory and how to manage memory allocation.

The user must allocate the DPA hugepages memory according to the section "Step 1: Allocate Hugepages". It is possible to use use a portion of the DPU memory allocation in the SNAP container as described in section "Adjusting YAML Configuration". This configuration includes the following minimum and maximum values:

• The minimum allocation which the SNAP container consumes:

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  resources:
    requests:
      memory: "4Gi"
          

• The maximum allocation that the SNAP container is allowed to consume:

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  resources:
    limits:
      hugepages-2Mi: "4Gi"
          

Hugepage memory is used by the following:

• SPDK mem-size global variable which controls the SPDK hugepages consumption (configurable in SPDK, 1GB by default)

• SNAP SNAP_MEMPOOL_SIZE_MB – used with non-ZC mode as IO buffers staging buffers on the Arm. By default, the SNAP mempool consumes 1G from the SPDK mem-size hugepages allocation. SNAP mempool may be configured using the SNAP_MEMPOOL_SIZE_MB global variable (minimum is 64 MB).

  Warning

  If the value assigned is too low, with non-ZC, a performance degradation could be seen.

• SNAP and SPDK internal usage – 1G should be used by default. This may be reduced depending on the overall scale (i.e., VFs/num queues/QD).

• XLIO buffers – allocated only when NVMeTCP XLIO is enabled.

The following is the limit of the container memory allowed to be used by the SNAP container:

            

            
resources:
  limits:
    memory: "6Gi"
        

The SNAP container also consumes DPU SHMEM memory when NVMe recovery is used (described in section "NVMe Recovery"). In addition, the following resources are used:

            

            
limits:
  memory: