[CPU] Refactor CPU unquantized linear

[bigPYJ1151]

Purpose

• Enable weight prepack for CPU unquantized linear

main

============ Serving Benchmark Result ============
Successful requests:                     64        
Maximum request concurrency:             16        
Benchmark duration (s):                  240.59    
Total input tokens:                      65472     
Total generated tokens:                  65536     
Request throughput (req/s):              0.27      
Output token throughput (tok/s):         272.39    
Total Token throughput (tok/s):          544.52    
---------------Time to First Token----------------
Mean TTFT (ms):                          3250.03   
Median TTFT (ms):                        3793.30   
P99 TTFT (ms):                           4976.67   
-----Time per Output Token (excl. 1st token)------
Mean TPOT (ms):                          55.60     
Median TPOT (ms):                        55.08     
P99 TPOT (ms):                           57.22     
---------------Inter-token Latency----------------
Mean ITL (ms):                           55.60     
Median ITL (ms):                         53.65     
P99 ITL (ms):                            58.88     
==================================================

this

============ Serving Benchmark Result ============
Successful requests:                     64        
Maximum request concurrency:             16        
Benchmark duration (s):                  199.05    
Total input tokens:                      65472     
Total generated tokens:                  65536     
Request throughput (req/s):              0.32      
Output token throughput (tok/s):         329.24    
Total Token throughput (tok/s):          658.17    
---------------Time to First Token----------------
Mean TTFT (ms):                          3185.62   
Median TTFT (ms):                        2737.65   
P99 TTFT (ms):                           4514.55   
-----Time per Output Token (excl. 1st token)------
Mean TPOT (ms):                          45.51     
Median TPOT (ms):                        46.10     
P99 TPOT (ms):                           46.72     
---------------Inter-token Latency----------------
Mean ITL (ms):                           45.51     
Median ITL (ms):                         44.16     
P99 ITL (ms):                            47.66     
==================================================

Test Plan

Unit tests

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request refactors the CPU unquantized linear operations to enable weight prepacking using oneDNN, which yields significant performance improvements as shown in the benchmarks. The changes are well-structured and introduce a DNNLScratchPadManager to handle memory for oneDNN primitives.

My review focuses on memory management within the new DNNLScratchPadManager. I've identified critical memory leaks that need to be addressed. Specifically, the manager leaks memory upon reallocation and lacks a destructor to free its buffer upon program exit.

[gemini-code-assist]

This realloc implementation has a memory leak. When a larger buffer is needed, it allocates a new one but doesn't free the old buffer pointed to by ptr_.

Additionally, std::aligned_alloc can return nullptr on allocation failure, which is not handled and could lead to crashes.

Please ensure the old buffer is freed and that allocation failures are handled. It's safer to allocate the new buffer first before freeing the old one.

Suggested change

	void DNNLScratchPadManager::realloc(size_t new_size) {
	new_size = round(new_size);
	if (new_size > size_) {
	ptr_ = std::aligned_alloc(64, new_size);
	size_ = new_size;
	}
	}
	void DNNLScratchPadManager::realloc(size_t new_size) {
	new_size = round(new_size);
	if (new_size > size_) {
	void* new_ptr = std::aligned_alloc(64, new_size);
	if (!new_ptr) {
	throw std::bad_alloc();
	}
	if (ptr_) {
	std::free(ptr_);
	}
	ptr_ = new_ptr;
	size_ = new_size;
	}
	}

[gemini-code-assist]

The DNNLScratchPadManager class allocates memory via std::aligned_alloc and manages it with the raw pointer ptr_, but it's missing a destructor. This will cause a memory leak when the static manager instance in get_dnnl_scratchpad_manager is destroyed at program exit.

To fix this, please add a destructor that frees the allocated memory.

Suggested change

	~DNNLScratchPadManager() {
	if (ptr_) {
	std::free(ptr_);
	}
	}