About

CactuBSSN was showing a 1-2% degradation in instruction counts with vector enabled. That has been fixed as of b7b387e1200f on the GCC trunk and we see roughly a 1% dynamic instruction count improvement.

Beyond fixing the regression, vector is not expected to provide much benefit for CactuBSSN. Testing on the k1 chip shows that 1.2% improvement in dynamic instruction counts using vector, but a 1% performance regression. As noted in the cam4 work item, we believe this is due to weaknesses in the k1 vector unit design.

Stakeholders/Partners

RISE:

Ventana: Jeff Law

External:

Dependencies

Status

Development	COMPLETE
Development Timeline	1H2024
Upstreaming	COMPLETE
Upstream Version	gcc-14 Spring 2024
Contacts	Jeff Law (Ventana)
Dependencies	None

Updates

May 28, 2024

Add data from run on the k1 (BPI-F3 board)

Mar 14, 2024

Regression has been fixed on the GCC trunk
Competitive data shows no significant improvement with vector
The 1% reduction in instruction counts we see with vector enabled is not likely to move the needle in any significant way performane-wise
Considering this done/closed.

Dec 29, 2023

Project reported as a priority for 1H2024