sys available memory不足

[AkinoMush1]

当前系统available为9.0G

               total        used        free      shared  buff/cache   available
Mem:            30Gi        21Gi       4.8Gi       233Mi       6.9Gi       9.0Gi

但是进行查询的时候报错sys available memory 1.40 GB less than low water mark 1.60 GB

SQL 错误 [1105] [HY000]: errCode = 2, detailMessage = [CANCELLED]Process has no memory available, cancel top memory used query: query memory tracker <Query#Id=a746c75ef01543ad-b0f50dcf257277c8> consumption 363.51 MB, backend 1.1.1.1 process memory used 16.21 GB exceed limit 24.42 GB or sys available memory 1.40 GB less than low water mark 1.60 GB. Execute again after enough memory, details see be.INFO.

这是为什么，明明系统可用内存足够。doris是怎么计算这个系统可用内存的

[AkinoMush1]

发现查询过程中是实时判断内存剩余量的