The SPDK NVMe initiator supports interrupt mode for transports that expose interrupt-capable queue pairs. This allows initiator applications to sleep when idle and wake on completion events instead of continuously polling, reducing CPU usage when the initiator is not under load.

Using spdk_nvme_perf

The spdk_nvme_perf application enables interrupt mode with the -E option. Interrupt mode is supported for local PCIe devices and for NVMe-oF RDMA initiators.

Example: Using spdk_nvme_perf in interrupt mode against an NVMe-oF RDMA target

perf -q 128 -o 4096 -w randread -E \
        -r 'trtype:RDMA adrfam:IPv4 traddr:192.168.100.8 trsvcid:4420 subnqn:nqn.2016-06.io.spdk:cnode1' \
        -t 300

Applications using the NVMe library directly may enable interrupt mode through spdk_nvme_ctrlr_opts.enable_interrupts. When enabled, interrupt-capable queue pairs may expose file descriptors through spdk_nvme_qpair_get_fd().

Operational notes

Interrupt mode is supported only in a primary SPDK process.
Secondary processes are not supported when interrupts are enabled.
Not all transports support interrupt-capable queue pairs. For the initiator side, PCIe and RDMA support interrupt mode.
The application must continue to drive completions correctly after wakeup (for example, through its poll-group or qpair completion path).

Verification

spdk_nvme_perf -E can be used to verify interrupt-mode behavior for both PCIe and RDMA initiators.
The regression test test/nvmf/host/interrupt.sh demonstrates expected initiator-side idle and busy transitions for NVMe-oF RDMA.