????Memcache?????Slab Allocator???????????:???????漲???С???????????????????????飬??????????????????
????Memcache??洢?漰??slab??page??chunk????????
????1??Chunk??????С???????????96Byte??
????2??page?????????????1??page?1M??
????3???????С??chunk????slab??
????Memcached?????????????-n??-f?????????????slab???????????Memcache???????1page????????1M??????????chunk????Щchunk??????????С??????????slab??
???????????????memcache???item?????
????1??  Memcache????item???С??key+value+flags???????????slab???????????item??slab??
????2??  ??????item?????slabδ?????????????1??page???????1M?????????memcached?????涼?????????????????item????slab?е?chunk
????3??  ???item?????slab????????????slab?????????expired??free_chunks????delete????1.2.2??delete??chunk????????????????????????chunk???д洢????ν????δ??ù???chunk??free_chunks_end?????д洢??
????4??  ???item?????slab???????????????slab????洢??????????????????μ?page?????page??????????С??chunk???????洢??
????5??  ???item?????slab???????????????slab????洢???????memcache???????????á??????lru???????item???????δ?????item????????????eviction++
?????????????
????1??  Delete??????????chunk?????????????????′???y???????????????chunk??
??????flush??
????1??  Flush????????????е?item?Ч???????????????????memcache???????????
?????Щ???
????1. memcache??????????治?????????????
????2. memcache????????slab????????????????????slab??
????3. flush_all????????memcache????????????????????е?item????????
????4. memcache??洢??item(key+value)??С?????1M??????page??С1M????
????5??????memcache?????????????????hash???????key???????????????????????ò????hash??????????????????п???????????????????????????????鹲??????memcached????????????????????????????hash??
????6?????memcached????????-M???????LRU?滻????????t??add??set???????
????7??memcached???????????????洢??????а?????????????楨???????????????????????????????????????????????????????????????????????
????8??memcache?洢??????key????????????php??C????????250