vmstat 명령어

vmstat 명령어

vmstat 명령어는 중요한 메모리 통계 정보에 대하여 요약된 정보를 제공해 줍니다.
시스템의 요약정보에는 free memory, free swap, and paging rates 정보등이 포함되어 있습니다.
-p 옵션을 함께 사용하면 세가지 클래스의 활성화된 페이징 , page in , page out 그리고 page-free 에 대한 정보를 보여 줍니다.

이 세가지 클래스는 다음과 같습니다.

- 파일시스템 페이징 (file system paging)
- 익명의 메모리 페이징 (anonymous memory paging)
- 실행가능한거나 공유가능한 라이브러리 페이징 ( executable/shared library paging )

# vmstat -p 3
     memory           page          executable      anonymous      filesystem
   swap  free  re  mf  fr  de  sr  epi  epo  epf  api  apo  apf  fpi  fpo  fpf
 411696 12720  38 35473 15738 0 217112 20 0  848   13 14146 14331 23  377  559
 409356 35344  11 1823 9717 0 141771 104  0   22   96 9376 9389   62  295  306
 345264 26724  53 5234 2329 0 8727  28    0    0  263 2200 2200  103  217  129
 301104 48032  36 7313 8451 0 102271 76   0   75  167 8199 8241   15  157  135

각 필드별 정의는 아래와 같습니다.

swap	Available swap space in Kbytes.
free	The amount of free memory as reported by vmstat, which reports the combined size of the cache list and free list. Free memory in Solaris may contain some of the file system cache.
re	Page reclaimsThe number of pages reclaimed from the cache list. Some of the file system cache is in the cache list, and when a file page is reused and removed from the cache list, a reclaim occurs. File pages in the cache list can be either regular files or executable/library pages.
mf	Minor faultsThe number of pages attached to an address space. If the page is already in memory, then a minor fault simply reestablishes the mapping to it; minor faults do not incur physical I/O.
fr	Page-freesKilobytes that have been freed either by the page scanner or by the file system (free-behind).
de	The calculated anticipated short-term memory shortfall. Used by the page scanner to free ahead enough pages to satisfy requests.
sr	The number of pages scanned by the page scanner per second.
epi	Executable and library page-insKilobytes of executable or shared library files paged in. An executable/library page-in occurs whenever a page for the executable binary or shared library is brought back in from the file system.
epo	Kilobytes of executable and library page-outs. Should be zero, since executable pages are typically not modified, there is no reason to write them out.
epf	Kilobytes of executable and library page-freesKilobytes of executable and library pages that have been freed by the page scanner.
api	Anonymous memory page-insKilobytes of anonymous (application heap and stack) pages paged in from the swap device.
apo	Anonymous memory page-outsKilobytes of anonymous (application heap and stack) pages paged out to the swap device.
apf	Anonymous memory page-freesKilobytes of anonymous (application heap and stack) pages that have been freed after they have been paged out.
fpi	Regular file page-insKilobytes of regular files paged in. A file page-in occurs whenever a page for a regular file is read in from the file system (part of the normal file system read process).
fpo	Regular file page-outsKilobytes of regular file pages that were paged out and freed, usually as a result of being paged out by the page scanner or by write free-behind (when free memory is less than lotsfree + pages_before_pager).
fpf	Regular file page-freesKilobytes of regular file pages that were freed, usually as a result of being paged out by the page scanner or by write free-behind (when free memory is less than lotsfree + pages_before_pager).