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.

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 (RDMA READ operation).

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

Behavior:

  • Fetches data from remote memory into local iovecs
  • Remote side does not participate (one-sided)
  • Completes asynchronously via callback

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 (RDMA WRITE operation).

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 ownership of a reference to the iovecs to libevpl. When set, libevpl takes ownership and will decrement the reference count when the RDMA write completes. When not set, libevpl adds its own reference and the caller retains ownership.

Behavior:

  • Pushes data from local iovecs to remote memory
  • Remote side CPU does not participate (one-sided)
  • Completes asynchronously via callback

See Also