Generate benchmark data with correct run length regardless of cardina…

…lity (rapidsai#11205)

Issue rapidsai#11204 

The new GPU-accelerated data generator does not account for run length when cardinality is not set.
This PR changes the logic so that the columns with correct average run length are generated even without specific cardinality.

Authors:
  - Vukasin Milovanovic (https://github.com/vuule)

Approvers:
  - Karthikeyan (https://github.com/karthikeyann)
  - David Wendt (https://github.com/davidwendt)
  - Nghia Truong (https://github.com/ttnghia)
  - https://github.com/nvdbaranec

URL: rapidsai#11205

cpp/benchmarks/common/generate_input.cu

@@ -397,19 +397,21 @@ std::unique_ptr<cudf::column> create_random_column(data_profile const& profile,
     random_value_fn<bool>(distribution_params<bool>{1. - profile.get_null_frequency().value_or(0)});
   auto value_dist = random_value_fn<T>{profile.get_distribution_params<T>()};
 
-  auto const cardinality                      = std::min(num_rows, profile.get_cardinality());
-  rmm::device_uvector<bool> samples_null_mask = valid_dist(engine, cardinality);
-  rmm::device_uvector<T> samples              = value_dist(engine, cardinality);
-
   // Distribution for picking elements from the array of samples
   auto const avg_run_len = profile.get_avg_run_length();
   rmm::device_uvector<T> data(0, cudf::default_stream_value);
   rmm::device_uvector<bool> null_mask(0, cudf::default_stream_value);
 
-  if (cardinality == 0) {
+  if (profile.get_cardinality() == 0 and avg_run_len == 1) {
     data      = value_dist(engine, num_rows);
     null_mask = valid_dist(engine, num_rows);
   } else {
+    auto const cardinality = [profile_cardinality = profile.get_cardinality(), num_rows] {
+      return (profile_cardinality == 0 or profile_cardinality > num_rows) ? num_rows
+                                                                          : profile_cardinality;
+    }();
+    rmm::device_uvector<bool> samples_null_mask = valid_dist(engine, cardinality);
+    rmm::device_uvector<T> samples              = value_dist(engine, cardinality);
     // generate n samples and gather.
     auto const sample_indices =
       sample_indices_with_run_length(avg_run_len, cardinality, num_rows, engine);