On Mon, 21 Jan 2019 17:53:45 +0100 Björn Töpel <bjorn.to...@gmail.com> wrote:
> > If that jump tables are a common problem, I wonder, why the compiler > > cannot be adapted to generate better performing code or an option passed > > to the compiler. > > > > It might make sense to use -fno-jump-tables or a better value for the > case-values-threshold param for the i40e code. However, doing that > would require a much broader testing, since there are a number of > different places where a switch-statement is used. And depending on > the context, a jump table might still be a better option. I recently found out that it is possible to disable GCC attributes per function basis. See how I played with it here: https://github.com/xdp-project/xdp-project/blob/master/areas/dma/dma01_test_hellwig_direct_dma.org#investigate-overhead-of-bpf-indirect-retpoline -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer
