ruby: add a couple of members to ruby objects to remove statics

Information
Submitter:	Brandon Potter
Repository:	gem5
Branch:	default
Bugs:
Depends On:
Reviewers
Groups:	Default
People:

Description

Changeset 11423:41c966b4e307
---------------------------
ruby: add a couple of members to ruby objects to remove statics

The block_size_bits and block_size_bytes members are added to all of the
ruby objects which previously relied on their respective 'RubySystem::'
variants. The goal is to pass in the values through Python parameter lists
and inheritance rather than rely on global variables to pass values.

This changeset does not modify the functions and methods to use the
the new members; that will happen in subsequent changesets with the goal of
providing some clarity to the new changes rather than a large indecipherable
changeset.

Testing Done

Issue Summary

Description	From	Last Updated	Status
Get this from the a parent? (See Tags.py) # Get the block size from the parent (system) block_size = Param.Int(Parent.cache_line_size, ...	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
I could have missed this, but doesn't GPU.py need to be updated?	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
Do all of these similar lines need to be update too?	Jason Lowe-Power	April 11, 2016, 4:01 p.m.	Dropped
Same as above. Should use parent as default	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
Parent as default	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
Ditto.	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
Ditto.	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open
Ditto.	Jason Lowe-Power	April 11, 2016, 1:30 p.m.	Open

Why did you choose to pass this parameter around to everything instead of keeping the canonical value with the RubySystem instance and changing the accessor to not be static (i.e., RubySystem::getBlockSizeBytes() to ruby_system->getBlockSizeBytes()). Most of these objects have a pointer to a RubySystem already. I really don't like having to change add this parameter to so many constructors, etc. The block size is inherent to the system, it shouldn't ever change (in a running system). Therefore, it should be a parameter at object creation (in the Python scripts), not a parameter every single time a function is called.
Let me know if this isn't clear, and I can point out in the patch where I would like to see this parameter removed. However, I think moving towards ruby_system->getBlockSizeBytes() will fix most places.
Also, there seems to be many place where this would need to be updated in the SLICC files (e.g., int l2_select_low_bit, default="RubySystem::getBlockSizeBits()";). I noted one below, but a quick grep reveals many others.
Finally, as noted below, in cases where the entire object needs the value, you should get the default value from the parent using Parent.cache_line_size. This will reduce the possibility for accidentally missing one place where someone forgot to change it.

src/gpu-compute/GPU.py (Diff revision 1)

Get this from the a parent? (See Tags.py)

    # Get the block size from the parent (system)
    block_size = Param.Int(Parent.cache_line_size, "block size in bytes")

Show all issues

Brandon Potter April 11, 2016, 4:01 p.m. (April 11, 2016, 4:01 p.m.)

This is a nice catch; nice way to pass in the value rather than having it hard coded as it is now. I'll fix this.

src/gpu-compute/shader.cc (Diff revision 1)