Re: [PATCH] selftests/sched_ext: Fix flaky ddsp failure tests on busy systems

[Tejun Heo]

On Tue, Aug 11, 2026 at 02:13:58PM +0000, Michal Blaszczyk wrote:
> The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling
> scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to find
> an idle CPU (returns -1). On loaded systems, this results in the tests
> skipping the very assertions they are meant to verify.
>
> Eliminate this flakiness by falling back to prev_cpu if no idle CPU is
> found, ensuring the illegal dispatch operations are unconditionally
> attempted and tested.

Applied to sched_ext/for-7.3 with the description updated to say that
scx_bpf_pick_idle_cpu() returns a negative error code on failure rather
than -1.

Thanks.

-- 
tejun