CoreMark performance drop with vector enabled on Saturn core (Rocket & Shuttle)

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Navyasree Kukatlapalli

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Mar 3, 2026, 9:32:42 AMMar 3
to Chipyard

Hi,

I am Navya. I am currently running CoreMark on the Saturn core with both Rocket and Shuttle configurations.

For the scalar configuration, I am getting around 2.5 CoreMarks, but when I enable the vector unit, the score drops to around 1.8 CoreMarks. I was expecting the performance to improve , but instead it is decreasing.

I am observing the same behavior with Shuttle as well. Shuttle is a dual-issue core, but even there I am getting only around 2.9 CoreMarks in scalar mode, which seems comparatively low for a dual-issue design.

The same behavior is observed in both Rocket+Saturn and Shuttle+Saturn configurations.

I would like to understand:

  • Is there any specific compiler flag required to properly enable vector instructions?

  • Does CoreMark need special build options to utilize the vector unit?

  • Could this drop be related to vector configuration parameters (VLEN, ELEN, LMUL, etc.)?

  • May I know what CoreMark score is typically expected for the Saturn core?

  • Is CoreMark a proper metric to evaluate vector performance, or is it mainly intended for scalar cores?

Any guidance on this would be very helpful.

Thank you,
Navya

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