Control pinned memory use with environment variables

cpp/src/utilities/host_memory.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "io/utilities/getenv_or.hpp"
+
 #include <cudf/detail/utilities/stream_pool.hpp>
 #include <cudf/logger.hpp>
 #include <cudf/utilities/error.hpp>
@@ -277,7 +279,7 @@ bool config_default_pinned_memory_resource(pinned_mr_options const& opts)
 CUDF_EXPORT auto& kernel_pinned_copy_threshold()
 {
   // use cudaMemcpyAsync for all pinned copies
-  static std::atomic<size_t> threshold = 0;
+  static std::atomic<size_t> threshold = getenv_or("LIBCUDF_KERNEL_PINNED_COPY_THRESHOLD", 0);
   return threshold;
 }
 
@@ -291,7 +293,7 @@ size_t get_kernel_pinned_copy_threshold() { return kernel_pinned_copy_threshold(
 CUDF_EXPORT auto& allocate_host_as_pinned_threshold()
 {
   // use pageable memory for all host allocations
-  static std::atomic<size_t> threshold = 0;
+  static std::atomic<size_t> threshold = getenv_or("LIBCUDF_ALLOCATE_HOST_AS_PINNED_THRESHOLD", 0);
   return threshold;
 }