Function: dvpp_malloc

Applicability

Function Usage

Allocates device memory for media processing. The allocated huge memory page meets the data processing requirements (for example, the start address is 128-byte aligned).

Prototype

• C Prototype

  1	aclError acldvppMalloc(void **devPtr, size_t size)

• Python Function

  1	dev_ptr, ret = acl.media.dvpp_malloc(size)

Parameter Description

Return Value Description

Restrictions

• After this API is called to allocate memory, the acl.media.dvpp_free API must be called to free the memory if the memory is not used.
• Performance will be compromised if acl.media.dvpp_malloc and acl.media.dvpp_free are called too frequently. You are advised to allocate or manage memory in advance to avoid unnecessary memory allocation and deallocation.
• When acl.media.dvpp_malloc is called to allocate memory, the allocation size is the input size rounded up to the nearest multiple of 32, plus 32 bytes.
• When the output of media data processing is used as the input of model inference, 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 128-byte aligned (ALIGN_UP[m,128]).
  

  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.

• If huge memory allocation by this API call fails, it only indicates that huge memory is insufficient.

  For the Atlas A2 training products / Atlas A2 inference products , the reserved huge page memory in the system is described in Overview.

• Media data processing can access up to 16 GB of address space in each process.

  This restriction applies to the following products:

  Atlas A3 training products / Atlas A3 inference products

  Atlas A2 training products / Atlas A2 inference products

  Atlas inference products

Reference

For details about the API call sequence and example, see Media Data Processing V1.