- Filed under Windows
- Original link at Technet: http://technet.microsoft.com/ko-kr/magazine/ff382715(en-us).aspx
Memory management is confusing, perhaps more so than any other aspect of PC performance. If you scour the Web for information on this topic, you will surely run into misguided advice and technical errors. Knowing the meaning of the following specialized memory-measurement terms helps you make sense of it all:
Physical memory refers to actual RAM chips or modules, typically installed on a computer’s motherboard. The amount of physical RAM available to Windows might be less than the total physical amount if another system component is using that memory for its own purposes, as is the case with “shared memory” video subsystems on portable computers. Physical memory measurements (total and in use) are reported on the Performance tab of Windows Task Manager and on the Memory tab of Resource Monitor.
Virtual memory consists of physical memory plus the amount of space in the page file, which is stored on the hard disk.
Kernel memory is owned by Windows and is used to provide system services to applications. Paged memory can be backed up to the page file and replaced by application memory if necessary. Nonpaged memory must remain in physical RAM at all times.
Cached memory holds data or program code that has been fetched into memory during the current session but is no longer in use now. If necessary, the Windows memory manager will flush the contents of cached memory to make room for newly summoned data.
Free memory represents RAM that does not contain any data or program code and is free for use immediately.
Working Set is the term that defines the amount of memory currently in use for a process. Private Working Set is the amount of memory that is dedicated to that process and will not be given up for other programs to use; Shareable Working Set can be surrendered if physical RAM begins to run scarce. Peak Working Set is the highest value recorded for the current instance of this process.
Commit Charge (commit size 라고도 불리운다.) 이는 현재 세션에서 프로그램이 터치한(commit한) 가상 메모리의 전체 합이며, 물리적 메모리로부터 디스크 기반의 페이지 파일로 페이지 아웃된 메모리를 포함한다. 작업관리자의 성능 탭에서 메모리와 물리 메모리 카운터는 모든 프로세스와 커널에 대한 이 값의 합이다. Commit Charge Limit은 모든 물리적 RAM과 페이지 파일의 전체 합이다 - 다르게 말하면, 최대 가상 메모리이다.
Hard faults Page faults라고도 알려져 있다. 이름이 주는 부정적인 이미지와 다르게, 이것은 에러 조건이 아니다. 이것은 OS 또는 어플리케이션이 필요로 하는, 물리적 메모리가 아닌 하드디스크의 페이지 파일로부터 fetch 되는 메모리 블록이다. 지속적인 높은 수의 초당 hard faults는 크거나 초과하는 가상 메모리 의존성을 의미하며, 결과적으로 성능에 악효과이다.
The best way to gauge the adequacy of your currently installed RAM is to keep an eye on the Memory graph in Resource Monitor.The green portion of the bar indicates the percentage of your physical memory that’s currently in use; shades of blue indicate cached memory that is available on demand (Standby). It’s also important to watch the green line on the graphs to the right, which indicates the number of hard faults per second your system is generating. If you see it spike off the top of the graph for extended periods of time, you’ll want to take a closer look at how memory is being used.
Pay special attention to these numbers when you’re asking the most of your computer—you might even consider performing a stress test by successively opening the applications you use most often. Switch between programs, open and edit some data files, browse a couple dozen Web pages, and generally try to use more system resources than you would use at one time under normal circumstances. If you find yourself bumping up against the ceiling regularly, you might get a noticeable performance boost from additional RAM.
Do not get hung up on percentages. If you routinely hit a maximum of 85 per¬cent memory usage on a machine running 64-bit Windows 7 with 6 GB of physical RAM, you have 900 MB of free RAM, which is plenty of headroom.