BVLC/caffe — pull request #411 by luotao1 (2014-05-13 06:41:42+00:00)
Title: remove im2col_cpu in Backward of conv_layer.cpp

If we don't need to save memory in CPU, we can store all `col_data`, and will not need to recompute them in backward pass `ConvolutionLayer::Backward_cpu` of conv_layer.cpp. This modify will reduce 5% time in our four-core CPU test.