Can You Capture Physical CPU-to-Memory Addresses in Real Time for Research?

[Fubini]

I'm doing some senior research into caching algorithms. In order to effectively evaluate some of our algorithms it would be amazing if we had access to physical addresses sent from the CPU to the memory captured in real time under real operating conditions. Does anyone know of a place that might have something like this in the public domain for research?

Alternately, would it hypothetically be possible to generate such a thing in software on a standard Intel processor running windows/linux whatever? Kernel hacking would not be out of the question.

Thanks,
David

 

[harborsparrow]

I think you want virtual addresses rather than physical ones

 

[rcgldr]

The issue with this is that it's done in hardware on most CPU's. The kernel only get's involved when there's an attempt to access a page that is not currently mapped in memory. I don't know if any CPU has a means to capture and/or report internal cache hits and/or page hits to some external device.

I don't know if running a virtual machine on an Intel or AMD cpu would provide this information. If so, that would be an alternative, although it would not be real time.

Perhaps something like a ARM cpu setup with sufficient pinouts to trace this information to an external device would be possible.

 

[harborsparrow]

The size and performance of L1, L2 and L3 cache varies from machine to machine, so there is no use in doing a study of that. But if you want to evaluate the performance of a specific machine, the traditional way is to find out exactly how the hardware caches work, and then simulate them with software. That way, you can run all kinds of programs against the simulations and see what's happening.

 

[LudusRex]

Thank you for your inquiry, David. It is certainly possible to generate physical addresses in software on a standard Intel processor running Windows or Linux. This can be achieved through kernel hacking, as you mentioned, or by using tools such as Intel's Performance Counter Monitor or Intel VTune Amplifier. These tools allow for the monitoring and analysis of various hardware events, including memory accesses and cache activity. However, it is important to note that generating physical addresses in this manner may not accurately reflect real-world operating conditions, as the software may not have access to all system resources and may not be able to accurately simulate the behavior of the CPU and memory.

As for publicly available data on physical addresses, there are some research papers and studies that have collected and analyzed this information, but it may be limited and specific to certain systems or architectures. Additionally, obtaining this data may require permission from the owners of the systems or hardware being studied.

Overall, while it is possible to generate physical addresses in software and access some publicly available data, it may be more beneficial to design experiments and simulations that can accurately reflect real-world operating conditions for your research on caching algorithms. I hope this information is helpful to you in your senior research. Best of luck!