Function: malloc

aclError aclrtMalloc(void **devPtr, size_t size, aclrtMemMallocPolicy policy)

dev_ptr, ret = acl.rt.malloc(size, policy)

Allocates size bytes of linear memory on the device and returns in dev_ptr a pointer to the allocated memory. The allocation size is the input size rounded up to the nearest multiple of 32 bytes, plus 32 bytes.

size: int, size of the allocated memory in bytes. The value cannot be 0.

policy: int, memory allocation rule. For details, see aclrtMemMallocPolicy.

dev_ptr: int, address of the pointer to the allocated device memory.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

• Media data processing has higher requirements on the memory for storing the input and output data (for example, the start address of the memory must be 128-byte aligned). Therefore, the following dedicated memory allocation APIs are required:
  • acl.media.dvpp_malloc: Allocates memory for the media data processing V1 API calls to perform operations such as cropping and resizing on images.
  • acl.himpi.dvpp_malloc: Allocates memory for the media data processing V2 API calls to perform operations such as cropping and resizing on images.
• The memory allocated by this API is not initialized. Call acl.rt.memset to initialize the memory and clear random numbers in the memory before using the memory.
• This API does not perform implicit device synchronization or stream synchronization. The memory allocation result, either success or failure, is returned immediately.
• Memory allocated by the acl.rt.malloc call needs to be freed by the acl.rt.free call.
• Performance deterioration will be caused by the frequent calling of acl.rt.malloc to allocate memory and acl.rt.free to free memory. You are advised to allocate or manage memory in advance to avoid frequent memory allocation and deallocation.
• The size of memory allocated by calling acl.rt.malloc is the input size rounded up to the nearest multiple of 32, plus 32 bytes.
  If you use this API to allocate a large memory block, and divide and manage the memory, each memory segment must meet the following requirements:

  • The memory size is rounded up to the nearest multiple of 32 plus 32 bytes (m = ALIGN_UP[len,32] + 32 bytes).
  • The memory start address must be 64-byte aligned (ALIGN_UP[m,64]).

  NOTE:

  len indicates the size of a memory segment. ALIGN_UP[len,k] indicates rounding up to a multiple of k bytes as in this formula: ((len – 1)/k + 1) x k.

For details about the API call example, see Data Copy.