???????????Linux??free??????????
??????????free?????н?????????4?С????????????????????к???????????free???????????????????FO(Free Output)?????磺
????FO[2][1] = 24677460
????FO[3][2] = 10321516

????free?????????????У?????????????????????????????????????total???????????used?????ж?????е????????free?????????????????????
????free????????к????????????????????????ж???????????????????????????????total??????????????????used???????????????????free????
????????е??????????????OS?????????????????OS??????????????????????:
????24677460KB?????free???λ?KB????????棬??FO[2][1]??
????????Щ???????????23276064KB????FO[2][2]??????????
????????1401396KB????FO[2][3]?????????
????????????????????
????FO[2][1] = FO[2][2] + FO[2][3]
????FO[2][4]?????????????????????????????deprecated?????????0????????Щ????????????0??????????free????????????????
????FO[2][5]?????OS buffer?????檔FO[2][6]?????OS cache????檔????Щ???buffer??cache??????????????á????????Щ???????????????????????????????????????:
????A buffer is something that has yet to be "written" to disk.
????A cache is something that has been "read" from the disk and stored for later use.
????????buffer??????????????disk?????豸????????????cache?????disk?????????????????????????IO??????????OS?????
????Linux??????????????????????windows??????????IO read??????????????cache?Щ?????????????FO[2][6]??cached memory????????FO[2][3]???С????????????????????????:
???????????cache?????????
????echo 3>/proc/sys/vm/drop_caches
????????????????????????
?????????????
?????????????????????????
????????ζ????????ο???????????????BerkeleyDB???????????????5G??????????????????????????????????ζ??????δ??????9???????
????free?????????????????ó?????????????????????
????????FO[3][2]????-buffers/cache??????????ó??????????????????棻
????????FO[3][3]????+buffers/cache??????????ó???????????ж?????棻
???????????cache??buffer??????????????????????????FO[3][3]??FO[2][3]?????
???????????????????
????FO[3][2] = FO[2][2] - FO[2][5] - FO[2][6]
????FO[3][3] = FO[2][3] + FO[2][5] + FO[2][6]
?????????????????
????free??????procps.*.rpm??????Redhat??е?OS?????free??????????????????/proc/meminfo?ж??????
???????????????meminfo(2)???????????????????/proc/meminfo???procps?????????????meminfo()????????????????????procps??tar???????????????????°??3.2.8??