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Modeling cache

 
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ShyamShankar



Joined: 14 Jan 2015
Posts: 34
Location: Kalady

PostPosted: Tue Jun 23, 2015 10:02 pm    Post subject: Modeling cache Reply with quote

Hi,
Can I model an instruction cache as virtually tagged physically indexed and data cache as physically tagged and physically indexed??
How do I change the tagging and indexing?? Is it possible??
I want to achieve accurate cache miss rates.
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DuncGrah
OVP Technologist
OVP Technologist


Joined: 27 Feb 2008
Posts: 1656
Location: United Kingdom

PostPosted: Wed Jun 24, 2015 1:30 am    Post subject: Reply with quote

Yes, you can get access to both the physical and virtual addresses of an access so you can model a cache as you require. These are passed, I believe, as part of the memory callbacks for an access. You would need to create a Full cache model, see example Imperas/Examples/Platforms/fullMMC

However, you say
Quote:
I want to achieve accurate cache miss rates.
but on an instruction accurate you can only achieve a level of approximation in line with the instruction accurate nature of the simulation.

It does mean that you can accurately compare the runs of multiple applications, it does NOT mean you can get accurate results as compared to hardware. On real hardware the cache is modified in various ways that would not be modeled, for example pipeline and pre-fetch effects.
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ShyamShankar



Joined: 14 Jan 2015
Posts: 34
Location: Kalady

PostPosted: Wed Jun 24, 2015 2:21 am    Post subject: Reply with quote

Could you explain a bit more as to how I can model the cache indexing and tagging??
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DuncGrah
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Joined: 27 Feb 2008
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PostPosted: Wed Jun 24, 2015 2:32 am    Post subject: Reply with quote

There are some examples of cache models using the MMC modeling component.
One such example can be found, as a configuration, at this location in an installation Imperas\ImperasLib\source\ovpworld.org\mmc\wb_1way_32byteline_2048tags\1.0\model with the common code that performs the modelling of the cache at this location in an installation Imperas\ImperasLib\source\ovpworld.org\mmc\support\1.0\include

Any other information is really down knowledge of cahce operation (there is lots of literature out there on this) and writing the C code to model the specific operation you require.
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ShyamShankar



Joined: 14 Jan 2015
Posts: 34
Location: Kalady

PostPosted: Wed Jun 24, 2015 7:51 pm    Post subject: Reply with quote

Thank You.
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