diff --git a/docs/additional-functionality/rapids-shuffle.md b/docs/additional-functionality/rapids-shuffle.md index 7c2ef5a3020..8e1e8731ce0 100644 --- a/docs/additional-functionality/rapids-shuffle.md +++ b/docs/additional-functionality/rapids-shuffle.md @@ -57,6 +57,13 @@ configuration can be independently changed for writers and readers using: `spark.rapids.shuffle.multiThreaded.[writer|reader].threads`. An appropriate value for these pools is the number of cores in the system divided by the number of executors per machine. +On the reader side, when blocks are received from the network, they are queued onto these threads +for decompression and decode. The amount of bytes we allow in flight per Spark task is +controlled by: `spark.rapids.shuffle.multiThreaded.maxBytesInFlight`, and it is set to +128MB-per-task as a default. Note that this memory comes from the Netty off-heap pool, and this +is sized at startup automatically by Netty, but this limit can be controlled by setting +`-Dio.netty.maxDirectMemory=[amount in Bytes]` under `spark.executor.extraJavaOptions`. + ## UCX Mode ---