spinlock

最新推荐文章于 2025-02-21 20:19:02 发布

原创最新推荐文章于 2025-02-21 20:19:02 发布 · 118 阅读

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本文探讨了Spinlock锁的工作原理及其应用场景，特别是在操作系统内核中。Spinlock通过忙等的方式保持循环检查锁状态，适用于锁定时间较短的情况。文章还介绍了两种避免忙等开销的方法：一是重新设计数据结构以减少或消除锁的需求；二是采用等待队列切换到其他线程（睡眠锁），以确保资源不会发生饥饿。

spinlock is a lock where the thread simply waits in a loop("spins") repeatedly checking until the lock becomes available.
-->it's busy waiting
-->only likely to be locked for a short period of time.this avoid overhead from operating system process re-scheduling or context switching.
-->often in operating system kernels.

quantum(分配量)
are two alternatives that avoid this:

1. Do not acquire the lock. In many situations it is possible to design data structures that do not require locking, e.g. by using per thread data, or by using per-cpu data and disabling interrupts.
2. Switch to a different thread while waiting (sometimes called sleeplocks). This typically involves attaching the current thread to a queue of threads waiting for the lock, then switching to another one. This scheme also has the advantages that it guarantees that resource starvation does not occur as long as all threads eventually relinquish locks they acquire and scheduling decisions can be made about which thread should progress first.