what is weight relating here in group_path synth command ?

[hariharan.gb]

Hi

In the synthesis command below:

DC Shell >> group_path -name <> -from <> -to <> -weight 2

what is this weight 2 represents in group path? can anyone explain exactly, what it does to our synthesis process ?

Thanks
Hariharan B

 

[yx.yang]

When DC do optimization, it will give more effort(such as run time) to path group with bigger weight.
By default, all the path are given the same default weight value.

 

[hariharan.gb]

Thanks Yang,

Can you please comment on the below as well.
If I am starting my synthesis, and say for example I have a critical path group violating with 3ns.
I have given set_path_group -name xxx -weight < 4 >

Correct me, if my understanding is wrong.
This means worst 4 path down from WNS will be given more importance and tool will try to fix these 4 paths as much as it can ( taking more time of tool).
If my understanding is correct - weight value varies from 0 -100, so 100 is the max path that is given to tool., we cant give more than that? correct ?

Thanks
Hariharan B

 

[yx.yang]

The weight number "4" just set the optimization priority of the pathes. When issue the path_group command you need tell DC which pathes will give the weight (in you case is 4) value. You can use -from/-to option of this command to identify the pathes, on which you want to apply the weight value. Please "man group_path" in DC.
That is: "4" just represent the priority of the path group. In that path group you can have 1 timing path or 100000 timing pathes.
By the way, command is "group_path", not "set_path_group".