PIP和PCP的区别

1. 优先继承协议(PIP)：
优先继承协议(PIP)是一种关键资源共享协议，用于在不同任务之间共享关键资源。这允许在不同的之间共享关键资源而不会发生无界的优先级反转。当任务发生优先级倒置时，优先级继承机制会提高具有关键资源的低优先级任务的优先级。它允许这个任务在不经过抢占的情况下尽早使用关键资源。它避免了无界的优先级倒置。

2. 优先上限协议(PCP)：
优先天花板协议 (PCP) 是优先继承协议 (PIP) 和最高储物柜协议 (HLP) 的扩展。解决了优先继承协议的无界优先级倒置、Highest Locker Protocol 的死锁和锁链问题，同时也最大限度地减少了Highest Locker Protocol 的局限性与继承相关的倒置。它不是像优先继承协议那样贪婪的方法。在 PCP 中，尽管资源是空闲的，但任务可能会被拒绝访问。

PIP和PCP的区别：

PRIORITY INHERITANCE PROTOCOL	PRIORITY CEILING PROTOCOL
It is a critical resource sharing protocol used for sharing critical resources among different tasks.	It is a critical resource sharing protocol which is an extension of PIP and HLP.
It overcomes the limitations of traditional resource sharing techniques.	It overcomes the limitations of PIP and HLP.
It requires minimum support from the operating system.	While it requires maximum support from the operating system.
It can not prevent the deadlock.	While it prevents tasks from going into deadlock.
Tasks using PIP may suffer chain blocking.	While the tasks using PCP can not suffer from chain blocking.
It is the simplest protocol among all resource sharing protocols.	While it is the complex and most efficient one among all.
It can not minimize the inheritance-related inversions.	While it is able to minimize the inheritance-related inversions.
It solves the problem of unbounded priority inversion.	While it solves the problem of unbounded priority inversion, deadlock and chain blocking.
In PIP, highest priority task can not be denied access if resource is free.	While in PCP, highest priority task can be denied access although resource is free if priority value is less than CSC (Current System Ceiling).
It is mostly used in small applications.	While it is used in large applications.