USM: High Velocity Linux Memory Manager Development
Craft custom, high-performance memory policies without touching the kernel. Go from idea to implementation in hours, not months, solving real-world bottlenecks like fragmentation and suboptimal caching.
The Problem: A 'One-Size-Fits-All' Kernel
The general-purpose Linux Memory Manager isn't optimized for specialized workloads, leading to performance spikes, memory fragmentation, and instability under pressure.
The Solution: A Microkernel-Inspired Architecture
USM solves this by moving memory management policy into an isolated userspace process, leaving only a minimal, safe mechanism in the kernel. This allows for rapid, safe development of application-aware strategies.
This is a Complete Memory Allocator
Writing a memory policy is now as simple as implementing a C function. Below is a complete, working 'first-fit' allocator.
policies/example_allocator.c
// A simple "first-fit" allocation policy
int basic_alloc_uniq(struct usm_event *event) {
// Lock to protect the shared free list
pthread_mutex_lock(&policiesSet1Flock);
if (list_empty(&freeList)) {
pthread_mutex_unlock(&policiesSet1Flock);
return 1; // Out of memory
}
// Get the first available page
struct optEludeList *freeListNode =
list_first_entry(&freeList, struct optEludeList, iulist);
// Reserve the page by removing it from the free list
list_del(&(freeListNode->iulist));
pthread_mutex_unlock(&policiesSet1Flock);
// Set the physical address for the kernel
event->paddr = freeListNode->usmPage->physicalAddress;
// Submit the mapping request to the kernel module
if (usmSubmitAllocEvent(event)) {
// On failure, roll back and return the page
pthread_mutex_lock(&policiesSet1Flock);
list_add(&(freeListNode->iulist), &freeList);
pthread_mutex_unlock(&policiesSet1Flock);
return 1; // Submission failed
}
// On success, link metadata and move to used list
usmLinkPage(freeListNode->usmPage, event);
pthread_mutex_lock(&policiesSet1Ulock);
list_add_tail(&(freeListNode->iulist), &usedList);
pthread_mutex_unlock(&policiesSet1Ulock);
return 0; // Success
}