Re: [PATCH 0/5] s390/idle: CPU idle driver

[Mete Durlu]

On 6/9/26 10:06, Christian Loehle wrote:
> On 6/9/26 08:52, Mete Durlu wrote:
> > This patch series introduces a CPU idle driver for s390
> > architecture that leverages the existing cpu idle infrastructure and
> > TEO (Timer Events Oriented) governor to optimize idle state selection
> > based on timer events and interrupt patterns.
> >
> > # Implementation Overview
> > -----------------------------------------------------------------------
> >
> > The driver implements two idle states;
> >
> > **Polling Idle (shallow state)**
> > - Busy-loop implementation that prevents SIE-exit during short idle periods
> > - Zero exit latency, optimized for latency-sensitive workloads
> > - Maintains CPU with the guest, improving response times
> >
> > **Enabled Wait (deep state)**
> > - Traditional EW state that signals hypervisor availability
> > - Higher exit latency but more efficient for longer idle periods
> >
> > The TEO governor dynamically selects between these states by monitoring
> > next timer interrupts and system interrupt frequency, choosing the most
> > appropriate idle state for each situation.
> I don't quite get the TEO focus of this series, on principle menu works
> similarly, did TEO just work much better for you?
> If so do you know why?

Hi,

there isn't a particular focus on any governor, just reading the
descriptions and trying to keep the solution initially simple lead
to using TEO. Users are free to select any other governor.

There was not a comparison run during benchmarks between TEO and
MENU, just an initial sniff test using a micro benchmark.