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PCLSRing (also known as Program Counter Lusering〔Program Counter LoSeRing, http://www.xxeo.com/archives/2006/06/29/vms.html〕) is the term used in the ITS operating system for a consistency principle in the way one process accesses the state of another process.〔(【引用サイトリンク】title=PCLSRing: Keeping Process State Modular )〕 ==Problem scenario== This scenario presents particular complications: *Process A makes a time-consuming system call. By "time-consuming", it is meant that the system needs to put Process A into a wait queue and can schedule another process for execution if one is ready-to-run. A common example is an I/O operation. *While Process A is in this wait state, Process B tries to interact with or access Process A, for example, send it a signal. What should be the visible state of the context of Process A at the time of the access by Process B? In fact, Process A is in the middle of a system call, but ITS enforces the appearance that ''system calls are not visible to other processes'' (or even to the same process). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「PCLSRing」の詳細全文を読む スポンサード リンク
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