How to disable L2/L3 cache in Intel® Core(TM) i7-4790 ?

[Rekha]

I am trying to find the memory bandwidth in my system.

My code does the following

1. get the start time

2. start the counters to measure cache-misses( using papi_counters)

3. do memory writes

4. stop the counter and read its value

5. get the end time; calculate the overall time needed for the memory access

Before executing this code I flush the cache so I can get all the memory writes as misses

Repeat the above steps for memory access of 32, 64, 128,256,512,1024 bytes

The time needed for doing memory access is 1035, 1050,1121,1078,1065,1112 useconds

I find the results to be weird, if the time taken for 32 access is X, then for 64 access shouldn't it be 2*X and soon on. Just had a thought of disabling L2 and L3 can help me find an answer to this issue. I did not any source on how to disable the L2/L3 cache.

Any suggestions would be really appreciated. 

It would be great if someone could help me, to figure out why is this misbehavior happening.

Thanks in advance

Regards

Rekha K R

[Alberto_Sykes]

Rekha, Thank you for posting in the Intel® Communities Support.

In reference to your inquiry, for us to be able to provide the most accurate assistance on this matter, we just wanted to confirm:

Is there any particular reason why you need this information?

Are you a software developer?

Are you working on a project?

If that is the case, what is that project about?

Any questions, please let me know.

Regards,

Albert R.

Intel Customer Support Technician

A Contingent Worker at Intel

[Rekha]

Is there any particular reason why you need this information?

I am doing my Master thesis based on CPU and memory management. I want to find the maximum bandwidth of my memory.

Are you a software developer?

NO.

Are you working on a project?

No, This work is a part of my Master thesis.

I need to find the maximum memory bandwidth, If there is a way to find without disabling my higher-level cache would also work for me. 

Regards

Rekha K R

[Alberto_Sykes]

Rekha, Thank you very much for providing those details.

In order to gather the information you are looking for, please visit, sign-in and submit your inquiry in the Intel® Software Forums Support, where you will receive further peer to peer technical assistance on this topic:

https://community.intel.com/t5/Software-Products/ct-p/software-products

Regards,

Albert R.

Intel Customer Support Technician

A Contingent Worker at Intel