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

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Message-Id: <20240410045417.3048209-1-quic_atulpant@quicinc.com>
Date: Wed, 10 Apr 2024 10:24:15 +0530
From: Atul Pant <quic_atulpant@...cinc.com>
To: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, rafael@...nel.org,
        daniel.lezcano@...aro.org
Cc: Atul Pant <quic_atulpant@...cinc.com>, kernel@...cinc.com,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: [RFC PATCH 0/2] Disable RT-throttling for idle-inject threads

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.

Atul Pant (2):
  sched/rt: Disable runtime accounting for idle threads with SCHED_FIFO
    policy
  sched/idle: Add a description for play_idle_precise

 kernel/sched/idle.c | 5 +++++
 kernel/sched/rt.c   | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

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2.25.1