loss become infinite while training quant models about qtool

[blueardour]

HI, @RaidenE1

There maybe many reasons for the loss NAN. I also frequently met such a problem. My general ways are:

1. empoly single GPU for training to see any error
2. close the quantization to verify whether the issue is caused by quantization or other problems
3. set all weight decay to zero (sometimes weight decay draw the quant scale to zero)
4. enable the wt_stable or fm_stable to allow a better initilization of quant scale (clip_val)
5. use a smaller learning rate and try another optimizer (sgd or adam)
6. check which tensor becomes NAN

Hope these tips help~