From 94005550703f85de9d1355dfa713d3250409d2c2 Mon Sep 17 00:00:00 2001 From: Richard Qin Date: Wed, 31 Dec 2025 18:16:24 +0800 Subject: dev log --- docs/dev/dev_memoty.md | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 docs/dev/dev_memoty.md (limited to 'docs') diff --git a/docs/dev/dev_memoty.md b/docs/dev/dev_memoty.md new file mode 100644 index 0000000..f05e336 --- /dev/null +++ b/docs/dev/dev_memoty.md @@ -0,0 +1,37 @@ +# Dev log +## **1. Process Management:** +The core architecture has been upgraded from a simple single queue to a Per-CPU scheduler, supporting multi-core concurrency. + +* Process lifecycle: A complete process state machine has been implemented, including UNUSED, RUNNABLE, RUNNING, SLEEPING, and ZOMBIE states. + +* Core operations: + * fork(): process cloning, supporting COW (copy-on-write) isolation of memory space between parent and child processes. + * exit(): process termination and resource cleanup. + * wait(): parent process waits for child process to exit. + * sleep()/wakeup(): channel-based sleep and wakeup mechanism. + +* Scheduling algorithm: + * O(1) priority scheduling has been implemented (supporting 4 priority queues). + + * Per-CPU RunQueue: each CPU has its own independent run queue. + + * Supports Work Stealing: idle CPUs can fetch tasks from other CPUs’ queues. + +## **2. Memory Management:** +A complete virtual and physical memory management system has been implemented. + +* Physical Memory (PMM): Implements the Buddy System, supporting memory allocation and deallocation in $2^n$ pages. + +* Virtual Memory (VM): Based on RISC-V Sv39 paging mode. Provides secure data copying from user space to kernel space (copyin). + +* COW (Copy-On-Write): During fork, only page table entries are copied and pages are set to read-only; writes trigger page faults for physical copy, greatly improving process creation efficiency. + +* Kernel heap: Implements a Slab Allocator, providing efficient allocation of small objects (such as struct Proc). + +## **3. Synchronization:** + +* Spinlock: Used to protect very short critical sections (e.g., scheduler lock, PMM lock), supports disabling interrupts to prevent deadlocks. + +* Mutex (sleeping lock): Used for long critical sections (e.g., file I/O), allowing sleep while holding the lock. + +* Lock Handoff: Implements a complex lock handoff mechanism in the scheduler to ensure atomicity of context switches. \ No newline at end of file -- cgit v1.2.3