MultiGPU

[FengLoveBella]

How to run your code on multi-GPU? Thank you very much.

[zhengyang-wang]

I haven't explored Tensorflow on multi-GPU currently.

[myhooo]

I add one GPU at the line "os.environ['CUDA_VISIBLE_DEVICES'] = '1,3'" in the main.py and the code can run on these two GPUs. @zhoufengbuaa

[John1231983]

I do not think so. For multiple GPU, you have to compute average gradient and batch normalization. It is very difficult. For easy, just compute average gradient and it will work. See the example of mnist dataset

[FengLoveBella]

@myhooo os.environ['CUDA_VISIBLE_DEVICES'] = '1,3' it is absolutely not ok, the gpu1 and gpu3 are allocated, but only the gpu1 is used for network.
@John1231983 I try a lot to use multi-gpu, I really compute average grads and average loss, but there is still some problem. reuse_variables and some else drive me crazy.

[FengLoveBella]

@zhengyang-wang It is very important to use large batch when semantic segmentation. Multi-gpu is absolutely a good chiose.

[myhooo]

@zhoufengbuaa Thank you for telling me that I am wrong~ ^_^

[zhengyang-wang]

@zhoufengbuaa I'm aware of that. However, there is an easy way as suggested by @John1231983, which is to use accumulated gradients. A similar way is used in the implementation of msc training. You can read my code to figure out how to do it. This approach allows you to use a large batch of larger patches, but it takes longer time to train.

[John1231983]

I thinl gradient is one one problem of multiple gpu. The another is syn. batch norm statistic that is not support in tensorflow now