GPU Plugin: Add bosch demo, update build instructions (#1872)

plugin/updater_gpu/README.md

@@ -39,7 +39,7 @@ A CUDA capable GPU with at least compute capability >= 3.5 (the algorithm depend
 
 Building the plug-in requires CUDA Toolkit 7.5 or later.
 
-The plugin also depends on CUB 1.5.2 - https://github.com/NVlabs/cub/tree/1.5.2
+The plugin also depends on CUB 1.6.4 - https://nvlabs.github.io/cub/
 
 CUB is a header only cuda library which provides sort/reduce/scan primitives.
 
@@ -70,6 +70,8 @@ The build process generates an xgboost library and executable as normal but cont
 ## Author
 Rory Mitchell 
 
-Report any bugs to r.a.mitchell.nz at google mail.
+Please report bugs to the xgboost/issues page. You can tag me with @RAMitchell.
+
+Otherwise I can be contacted at r.a.mitchell.nz at gmail.
 
 

plugin/updater_gpu/src/device_helpers.cuh

@@ -414,7 +414,6 @@ class bulk_allocator {
     }
 
     _size = get_size_bytes(args...);
-    std::cout << "trying to allocate: " << _size << "\n";
 
     safe_cuda(cudaMalloc(&d_ptr, _size));
 

plugin/updater_gpu/src/gpu_builder.cu

@@ -311,7 +311,6 @@ float GPUBuilder::GetSubsamplingRate(MetaInfo info) {
   uint32_t max_nodes_level = 1 << param.max_depth;
   size_t required = 10 * info.num_row + 40 * info.num_nonzero
     + 64 * max_nodes + 76 * max_nodes_level * info.num_col;
-  std::cout << "required: " << required << "\n";
   size_t available = dh::available_memory();
   while (available < required) {
     subsample -= 0.05;