RDMA

libevpl supports one-sided READ/WRITE RDMA operations, wherein the initiator reads from or writes to memory in a remote machine without software involvement on the remote system.

Backends

libevpl provides two backends for RDMA operations:

• Native RDMA (EVPL_STREAM_RDMACM_RC) - Hardware-accelerated RDMA via RDMACM
• TCP-RDMA (EVPL_DATAGRAM_TCP_RDMA) - RDMA emulation over TCP for development and testing without RDMA hardware

Functions

evpl_rdma_read

void evpl_rdma_read(
    struct evpl *evpl,
    struct evpl_bind *bind,
    uint32_t remote_key,
    uint64_t remote_address,
    struct evpl_iovec *iov,
    int niov,
    void (*callback)(int status, void *private_data),
    void *private_data);

Read data from remote memory into local buffers.

Parameters:

• evpl - Event loop
• bind - RDMA connection
• remote_key - Memory key for remote buffer
• remote_address - Address of remote buffer
• iov - Local buffers to read into
• niov - Number of local buffers
• callback - Completion callback
• private_data - User context

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evpl_rdma_write

void evpl_rdma_write(
    struct evpl *evpl,
    struct evpl_bind *bind,
    uint32_t remote_key,
    uint64_t remote_address,
    struct evpl_iovec *iov,
    int niov,
    unsigned int flags,
    void (*callback)(int status, void *private_data),
    void *private_data);

Write data from local buffers to remote memory.

Parameters:

• evpl - Event loop
• bind - RDMA connection
• remote_key - Memory key for remote buffer
• remote_address - Address of remote buffer
• iov - Local buffers containing data to write
• niov - Number of local buffers
• flags - RDMA flags (see below)
• callback - Completion callback
• private_data - User context

Flags:

• EVPL_RDMA_FLAG_TAKE_REF - Transfer iovec ownership to libevpl

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evpl_bind_is_rdma

int evpl_bind_is_rdma(struct evpl_bind *bind);

Check if a bind supports RDMA operations.

Parameters:

• bind - Connection to check

Returns: Non-zero if RDMA operations are supported, 0 otherwise

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See Also

• Binds & Connections API - RDMA connection setup
• Memory API - Buffer management
• Protocols - Available protocols including TCP-RDMA