How to increase GS bandwidth in Gluten via prefetch level?

[sumokiama]

I wish to increase the GS bandwidth in Gluten. The only prefetch controls that I can find are:
spark.gluten.sql.columnar.backend.velox.prefetchRowGroups
spark.gluten.sql.columnar.backend.velox.cachePrefetchMinPct

What values should be used to increase the GS bandwidth for TPCDS Q3 for example.
In the TPCH document I see
spark.gluten.sql.columnar.backend.velox.prefetchRowGroups=1
spark.gluten.sql.columnar.backend.velox.cachePrefetchMinPct=80

These don't appear to do anything to change the GS bandwith.
I've also played with executor/core settings but the GS bandwidth remains static.
Are there other configuration settings?

[sumokiama]

This setting appears to do the trick:
spark.gluten.sql.columnar.backend.velox.IOThreads