Function: host_register

Applicability

Product	Supported (√/x)
Atlas A3 training products/Atlas A3 inference products	√
Atlas A2 training products/Atlas A2 inference products	√
Atlas training products	√
Atlas inference products	x
Atlas 200I/500 A2 inference products	x

Function Usage

Maps and registers the host memory as an address accessible to the device for the NIC on the device to access. The mapped device address cannot be used for memory copy.

This API is used in pairs with acl.rt.host_unregister.

Prototype

C Prototype

aclError aclrtHostRegister(void *ptr, uint64_t size, aclrtHostRegisterType type, void **devPtr)

Python Function

dev_ptr, ret = acl.rt.host_register(ptr, size, type)

Parameter Description

Parameter	Description
ptr	Int, host memory address. The host memory address must be 4K-page-aligned. If the OS kernel version is 5.10 or earlier, using non-lock page memory will cause exceptions. In this case, you must call acl.rt.malloc_host to allocate the host memory. If the OS kernel version is later than 5.10, non-lock page memory can be used, so acl.rt.malloc_host is not required for allocating the host memory.
size	Int, memory size, in bytes.
type	Int, memory registration type. Currently, only ACL_HOST_REGISTER_MAPPED is supported, indicating that the host memory is mapped and registered as an address accessible to the device.

Return Value Description

Return Value	Description
dev_ptr	Int, memory address mapped from the host and accessible to the device.
ret	Int, error code: 0 on success; else, failure.

Parent topic: Memory Management