Frequently Asked Questions

Q: Why does the CPI-stack format that I generate with Sniper differ from the SC11 paper results?

A: We have recently updated the CPI stack format to better reflect system resource contention. See our recent IISWC publication for more details on these changes.

Q: Why does the TLB code in Sniper not perform the way that I expect?

A: Sniper is a user-space simulator, and therefore doesn't model all of the Hardware-Operating System interactions that one might expect to see. This is because the applications that we are targeting, HPC workloads, tend to see very few TLB misses. As an experiment, we looked into modeling the OS effects of TLB misses, but only from the perspective of OS-handled TLB misses. To use this, one would have to set the TLB size to the last-level TLB of the architecture that you are modeling, and set the miss penalty to 100s of cycles to account for the OS penalty. Modeling L1-TLBs is possible but is not currently implemented. Modifications to the memory subsystem to report TLB misses as a part of the load and store access times would be necessary to get this working properly.

Q: What are the license terms for using Sniper?

A: In short, the interval core model is protected under a US patent application. We automatically grant you a free license for using the interval model inside Sniper for academic purposes. For commercial use, please contact Lieven Eeckhout. All other code is licensed under the very liberal MIT license. You can view the full details on our License page.