Koen Verbeeck looks at an update to AutoAdjustBufferSize in SSIS 2016 CU1:
Anyway, one of the particular updates that caught my attention was Adds the adjusted buffer size to the BufferSizeTuning event when AutoAdjustBufferSize is enabled in SSIS 2016. In simple terms, it allows you to log the size of the data flow buffer set automatically by the AutoAdjustBufferSizeproperty. This property basically automatically calculates the buffer size needed to reach the amount of rows in the buffer specified by DefaultBufferMaxRows. Therefore, it ignores the DefaultBufferSize property. Unfortunately, this new property is set to false by default.
Logging is at the Verbose level, so you won’t use it very often, but for test purposes, it’s interesting to see those changes.