Memory organization based on data temperature

基于数据温度的内存组织

• 批准号: 503509-2016
• 负责人: Dueck, Gerhard
• 金额: $ 1.89万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618877
• 关键词: Memory; organization; based; data; temperature

Memory management is an essential part of any software system. Programming languages offer different degrees of support. Objects allocated in memory have varying life times. Objects that are accessible from the rootset or from another live object are said to be alive. In contrast, objects that can no longer be accessed are said to be dead. In some languages, for example C, the programmer is responsible to free the memory of dead objects before they become unreachable. In other languages, for example Java, a garbage collector is responsible for collecting dead objects. Some objects persist for a long time but they are seldom accessed; these objects are said to be cold. It has been shown that it is advantageous to move cold object to regions that are not touched by the garbage collector. Since these regions are infrequently accessed, they can be paged out to disk. Sequestering cold objects into special areas will help both the real memory footprint as well as cache coherence.With the proliferation of persistent memory it is possible to store regions with cold objects in such memory. The term used for persistent storage is NVRAM (Non-Volatile Random Access Memory). NVRAM is less costly than dynamic RAM with slightly higher access time. The main application for NVRAM has been in the area of database transactions. Here, we plan to use it to sequester cold objects in NVRAM. The main objective of the proposed research is to increase the effectiveness of garbage collection by making use of persistent memory. Some properties of cold objects will be investigated. How are cold objects detected? When should they be moved to a cold area? When should they move back from the cold area? When shouldthey be garbage collected? The answer to these questions will guide the development, implementation, and testing of software generated for inclusion in the garbage collection strategies of the IBM J9 product as well as the OMR Eclipse project.

内存管理是任何软件系统的重要组成部分。编程语言提供不同程度的支持。内存中分配的对象具有不同的生命周期。可从根集或另一个活动对象访问的对象被称为活动对象。相反，无法再访问的对象被称为死亡对象。在某些语言中，例如 C，程序员负责在死对象变得不可访问之前释放它们的内存。在其他语言中，例如Java，垃圾收集器负责收集死对象。有些对象会持续很长时间，但很少被访问；据说这些物体是冷的。已经表明，将冷对象移动到垃圾收集器不接触的区域是有利的。由于这些区域不经常访问，因此可以将它们分页到磁盘。将冷对象隔离到特殊区域将有助于实际内存占用以及缓存一致性。随着持久内存的扩散，可以在此类内存中存储具有冷对象的区域。用于持久存储的术语是 NVRAM（非易失性随机存取存储器）。 NVRAM 比动态 RAM 成本低，但访问时间稍长。 NVRAM 的主要应用是数据库事务领域。在这里，我们计划用它来隔离 NVRAM 中的冷对象。本研究的主要目标是通过利用持久内存来提高垃圾收集的有效性。将研究冷物体的一些特性。如何检测冷物体？什么时候应该将它们转移到寒冷地区？他们什么时候应该从寒冷地区搬回来？什么时候应该对它们进行垃圾收集？这些问题的答案将指导所生成的软件的开发、实现和测试，这些软件将包含在 IBM J9 产品以及 OMR Eclipse 项目的垃圾收集策略中。