Re: [PATCH v8 01/11] cpuidle/poll_state: poll via smp_cond_load_relaxed()

[Christoph Lameter (Ampere)]

On Wed, 16 Oct 2024, Catalin Marinas wrote:

> The behaviour above is slightly different from the current poll_idle()
> implementation. The above is more like poll every timeout period rather
> than continuously poll until either the need_resched() condition is true
> _or_ the timeout expired. From Ankur's email, an IPI may not happen so
> we don't have any guarantee that WFET will wake up before the timeout.
> The only way for WFE/WFET to wake up on need_resched() is to use LDXR to
> arm the exclusive monitor. That's what smp_cond_load_relaxed() does.

Sorry no. The IPI will cause the WFE to continue immediately and not wait
till the end of the timeout period.