Lost RAM的統計方法

最近遇到一個Lost RAM占用內存達到1.5GB的問題，所以先統計一下Lost RAM的計算方法：

根據計算公式：

            long lostRAM = memInfo.getTotalSizeKb() - (totalPss - totalSwapPss)
                    - memInfo.getFreeSizeKb() - memInfo.getCachedSizeKb()
                    - memInfo.getKernelUsedSizeKb() - memInfo.getZramTotalSizeKb();

解讀：

Lost RAM=total memory(減掉kernel reserve部分)-(process total pss - swap占用空間總和(除去native process所占用swap空間))-dumpsys meminfo（free+cached kernel+kernel+ZRAM used見下文） 

即：Lost ram=883248-（193417+476988-74453）-（64008+81368+100892+59368）=-18340

Total RAM:   883,248K (status normal)
 Free RAM:   338,793K (  193,417K cached pss +    81,368K cached kernel +    64,008K free)
 Used RAM:   577,880K (  476,988K used pss +   100,892K kernel)
 Lost RAM:   -18,340K
     ZRAM:    59,368K physical used for   179,388K in swap (  661,184K total swap)
   Tuning: 128 (large 256), oom   184,320K, restore limit    61,440K (low-ram)