Hi, I use nn.DataParallel
to use multi GPU; However it seems that multi-gpu
don’t speed up in any aspect.
the details in one epoch are as belowed:
Two GPUs:
Batch_size Loss Time(s)
64 256 320
128 140 324
256 78 330
And Using One GPU:
Batch_size Loss Time(s)
64 250 290
128 137 298
256 77 260
The result really confuses me a lot. so what and where the Multi GPU works for?
In one epoch , the time is almost the same.
PS:
I use the Multi GPU just with nn.Dataparallel
model = model.cuda()
model = nn.Dataparallel(model)
Update:
Multi GPU is for larger batch_size , is it right? larger batch, faster convergence?