in x-pack monitoring Indexing Rate

I am not sure I understand your question. Could you please clarify and provide some additional details and context?
the x-pack monitoring to see the add file into es ,
the Indexing Rate not Unstable 30s goto 1,000,000 /s 30s goto 500,000/s, not a straight line
use the esrally to test the es performance ,link the flow update images

What does it look like if you zoom in?
in x-pack monitoring the use Last 30 minutes search and 10s flush,
i want the line link the flow images

can cloes,
i find this is esrally client read file promble.
the read spead no all ok.
thanks. all.