linux-kernel - Re: [RFC PATCH 0/2] Disable RT-throttling for idle-inject threads

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Message-ID: <20240410093127.29e81d9f@gandalf.local.home>
Date: Wed, 10 Apr 2024 09:31:27 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Atul Pant <quic_atulpant@...cinc.com>
Cc: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
 vincent.guittot@...aro.org, dietmar.eggemann@....com, bsegall@...gle.com,
 mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
 rafael@...nel.org, daniel.lezcano@...aro.org, kernel@...cinc.com,
 linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [RFC PATCH 0/2] Disable RT-throttling for idle-inject threads

On Wed, 10 Apr 2024 10:24:15 +0530
Atul Pant <quic_atulpant@...cinc.com> wrote:

> We are trying to implement a solution for thermal mitigation by using
> idle injection on CPUs.  However we face some limitations with the
> current idle-inject framework. As per our need, we want to start
> injecting idle cycles on a cpu for indefinite time (until the
> temperature/power of the CPU falls below a threshold). This will allow
> to keep the hot CPUs in the sleep state until we see improvement in
> temperature/power. If we set idle duration to a large value or have an
> idle-injection ratio of 100%,  then the idle-inject RT thread suffers
> from RT throttling. This results in the CPU exiting from the sleep state
> and consume some power.
> 
> To solve this limitation, we propose a solution to disable RT-throttling
> whenever idle-inject threads run. We achieve this by not accounting the
> runtime for the idle-inject threads.

I'm going to assume that when dl-server is finally accepted, this will no
longer be an issue for you?

  https://lore.kernel.org/all/cover.1699095159.git.bristot@kernel.org/

-- Steve