5. Supporting Structures#

5.1. `cuObjScatterGatherEntry`#

typedef struct cuObjScatterGatherEntry {
    void* addr;
    size_t size;
} cuObjScatterGatherEntry_t;

Fields:

addr: Host memory address.
size: Segment size in bytes.

5.2. `cuObjScatterGatherEntryWithOffset`#

typedef struct cuObjScatterGatherEntryWithOffset {
    loff_t offset;
    size_t size;
} cuObjScatterGatherEntryWithOffset_t;

Fields:

offset: Offset from the base registered buffer.
size: Segment size in bytes.

5.3. `cuObjAsyncEvent_t`#

typedef struct cuObjAsyncEvent_s {
    void* async_handle;
    ssize_t status;
} cuObjAsyncEvent_t;

Fields:

async_handle: User handle provided during asynchronous submission.
status: Completion status. The field is declared as ssize_t, but poll() stores an enum ibv_wc_status value in it. IBV_WC_SUCCESS (0) means success. For nonzero values, interpret the field as ibv_wc_status_str((enum ibv_wc_status)event.status).

5.4. `cuObjRDMATunableParam`#

struct cuObjRDMATunableParam {
    int num_dcis;
    unsigned cq_depth;
    unsigned long dc_key;
    int ibv_poll_max_comp_event;
    int service_level;
    uint8_t timeout;
    unsigned hop_limit;
    int pkey_index;
    int max_wr;
    int max_sge;
    uint32_t delay_interval;
    cuObjDelayMode_t delay_mode;
    bool qp_reset_on_failure;
    uint8_t retry_cnt;
    unsigned traffic_class;
    int max_rd_atomic;
};

5.5. `cuObjRDMATunable`#

cuObjRDMATunable stores cuObjRDMATunableParam values and provides getters and setters.

Parameter	Setter	Getter	Default	Valid Values / Current Behavior
`num_dcis`	`setNumDcis(int)`	`getNumDcis()`	`128`	Number of channels/DCIs. Must be usable by the RDMA device. Values greater than the device QP limit cause session start failure.
`cq_depth`	`setCqDepth(unsigned)`	`getCqDepth()`	`640`	Completion queue depth.
`dc_key`	`setDcKey(unsigned long)`	`getDcKey()`	`0xffeeddcc`	DC key value.
`ibv_poll_max_comp_event`	`setIbvPollMaxCompEv(int)`	`getIbvPollMaxCompEv()`	`0`	Not used currently.
`service_level`	`setServiceLevel(int)`	`getServiceLevel()`	`0`	Service level value.
`timeout`	`setTimeout(uint8_t)`	`getTimeout()`	`16`	Timeout value used by the RDMA connection.
`hop_limit`	`setHopLimit(unsigned)`	`getHopLimit()`	`4`	Hop limit value.
`pkey_index`	`setPkeyIndex(int)`	`getPkeyIndex()`	`0`	Partition key index.
`max_wr`	`setMaxWr(int)`	`getMaxWr()`	`0`	Not used currently.
`max_sge`	`setMaxSge(int)`	`getMaxSge()`	`10`	Maximum scatter-gather entries per operation. `handleGetObject()` and `handlePutObject()` fail with `-EIO` if the registered buffer entry count exceeds this value.
`delay_interval`	`setDelayInterval(uint32_t)`	`getDelayInterval()`	`5000`	Polling delay interval in nanoseconds.
`delay_mode`	`setDelayMode(cuObjDelayMode_t)`	`getDelayMode()`	`CUOBJ_DELAY_BATCH`	One of the `cuObjDelayMode_t` values.
`qp_reset_on_failure`	`setQPResetOnFailure(bool)`	`getQPResetOnFailure()`	`true`	Enables queue-pair reset after completion failure.
`retry_cnt`	`setRetryCount(uint8_t)`	`getRetryCount()`	`7`	Retry count value. The header documents this as a 3-bit value, 0 through 7.
`traffic_class`	`setTrafficClass(unsigned)`	`getTrafficClass()`	`96`	Values below 256 are applied. Values greater than or equal to 256 are logged as invalid.
`max_rd_atomic`	`setMaxRdAtomic(uint8_t)`	`getMaxRdAtomic()`	`0`	`0` means auto-detect from the RDMA device. Setting `MaxRdAtomic` to 16 is required for optimal performance on PUT operations using `RDMA_READ`. Positive values are capped to the device maximum.

The setters do not return status values and do not perform full range validation. Configure values that are valid for the RDMA device and workload.