pnowojski edited a comment on issue #8455: [FLINK-12284][Network,Metrics]Fix 
the incorrect inputBufferUsage metric in credit-based network mode
URL: https://github.com/apache/flink/pull/8455#issuecomment-496138201
 
 
   @Aitozi :
   
   I think your proposal makes sense. Having 3 metrics for credit based flow 
control sounds as the best, the most explicit solution for me.
   
   > Hi @pnowojski , what is the reason for the second point ?
   
   Which second point did you mean @Aitozi ? Or did @zhijiangW answer your 
question?
   
   @zhijiangW :
   
   > Maybe my previous expression is not very clear. If floating buffers are 
used, I only mean the exclusive buffers for one/some RemoteInputChannels are 
also expected to be used eventually, but not indicate the exclusive buffers for 
all the channels are used.
   
   👍
   
   I meant that from the perspective of such data skew, just knowledge of 
`floating` buffers usage is not enough for performance tuning. 
   
   If you see that `floating` buffers usage is constantly jumping, between 
empty & full, it means that you should probably increase the either floating 
buffer pool or exclusive buffer pool. Now depending if you have a data skew and 
mostly unused `exclusive` buffers, you would be better off increasing 
`floating` buffer pool and potentially shrinking `exclusive`. While if you do 
not have data skew (and mostly used `exclusive` buffer pool % a couple of 
idling channels), you would be better off increasing `exclusive` buffer pool.

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