Function: malloc_align32

Applicability

Product	Supported
Atlas 350 Accelerator Card	√
Atlas A3 training product / Atlas A3 inference product	√
Atlas A2 training product / Atlas A2 inference product	√
Atlas training product	√
Atlas inference product	√
Atlas 200I/500 A2 inference product	√

Description

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. Memory allocated by this call needs to be freed by the acl.rt.free call.

Compared with acl.rt.malloc, this API only rounds the input size up to the nearest multiple of 32 bytes, but does not add an extra 32 bytes.

Prototype

C Prototype

        
             aclError aclrtMallocAlign32(void **devPtr, size_t size, aclrtMemMallocPolicy policy)

Python Function

        
             dev_ptr, ret = acl.rt.malloc_align32(size, policy)

Parameters

Parameter	Description
size	Int, allocated memory size, in bytes. Must not be 0.
policy	Int, memory allocation policy. If the configured memory allocation rule exceeds the value range of aclrtMemMallocPolicy and size is greater than or equal to 2 MB, memory is allocated based on huge pages. Otherwise, memory is allocated based on normal pages.

Return Value

Return Value	Description
dev_ptr	Int, address of the pointer to the allocated device memory.
ret	Int, error code. 0 on success; else, failure.

Restrictions

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:
- When the media data processing V1 API is called to perform operations such as cropping and resizing on images, the acl.media.dvpp_malloc API is called to allocate memory.
- When the media data processing V2 API is called to perform operations such as cropping and resizing on images, the acl.himpi.dvpp_malloc API is called to allocate memory.

The memory allocated by this API does not initialize the content.

This API does not perform implicit device synchronization or stream synchronization. The memory allocation result, either success or failure, is returned immediately.
If the memory is allocated by using acl.rt.malloc_align32, the memory needs to be released by calling acl.rt.free.
Performance deterioration will be caused by the frequent calling of acl.rt.malloc_align32 to allocate memory and acl.rt.free to free memory. You are advised to allocate or manage memory in advance to avoid frequent memory application and freeing.
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]).
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.

Parent topic: Memory Management