linux-kernel - [PATCH 0/2] clocksource: Avoid incorrect hpet fallback

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Message-Id: <20211110221732.272986-1-longman@redhat.com>
Date:   Wed, 10 Nov 2021 17:17:30 -0500
From:   Waiman Long <longman@...hat.com>
To:     John Stultz <john.stultz@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Cassio Neri <cassio.neri@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Colin Ian King <colin.king@...onical.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Feng Tang <feng.tang@...el.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Waiman Long <longman@...hat.com>
Subject: [PATCH 0/2] clocksource: Avoid incorrect hpet fallback

It was found that when an x86 system was being stressed by running
various different benchmark suites, the clocksource watchdog might
occasionally mark TSC as unstable and fall back to hpet which will
have a signficant impact on system performance.

The current watchdog clocksource skew threshold of 50us is found to be
insufficient. So it is changed back to 100us before commit 2e27e793e280
("clocksource: Reduce clocksource-skew threshold") in patch 1. Patch 2
adds a Kconfig option to allow kernel builder to control the actual
threshold to be used.

Waiman Long (2):
  clocksource: Avoid accidental unstable marking of clocksources
  clocksource: Add a Kconfig option for WATCHDOG_MAX_SKEW

 kernel/time/Kconfig       |  9 ++++++
 kernel/time/clocksource.c | 58 ++++++++++++++++++++++++++++++---------
 2 files changed, 54 insertions(+), 13 deletions(-)

-- 
2.27.0