From: Thomas Gleixner <tglx@linutronix.de>
To: paulmck@kernel.org, Feng Tang <feng.tang@intel.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>,
John Stultz <john.stultz@linaro.org>,
Stephen Boyd <sboyd@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
Mark Rutland <Mark.Rutland@arm.com>,
Marc Zyngier <maz@kernel.org>, Andi Kleen <ak@linux.intel.com>,
Chris Mason <clm@fb.com>, LKML <linux-kernel@vger.kernel.org>,
lkp@lists.01.org, lkp@intel.com
Subject: Re: [LKP] Re: [clocksource] 6c52b5f3cf: stress-ng.opcode.ops_per_sec -14.4% regression
Date: Fri, 23 Apr 2021 21:14:49 +0200 [thread overview]
Message-ID: <87tunwvmmu.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210422142454.GD975577@paulmck-ThinkPad-P17-Gen-1>
On Thu, Apr 22 2021 at 07:24, Paul E. McKenney wrote:
> On Thu, Apr 22, 2021 at 03:41:26PM +0800, Feng Tang wrote:
> So what are our options?
>
> 1. Clear CLOCK_SOURCE_MUST_VERIFY from tsc-early.
>
> 2. #1, but add tsc-early into the watchdog list and set
> CLOCK_SOURCE_MUST_VERIFY once it is better calibrated.
>
> 3. Add a field to struct clocksource that, if non-zero, gives
> the maximum drift in nanoseconds per half second (AKA
> WATCHDOG_INTERVAL). If zero, the WATCHDOG_MAX_SKEW value
> is used. Set this to (say) 150,000ns for tsc-early.
>
> 4. As noted earlier, increase WATCHDOG_MAX_SKEW to 150 microseconds,
> which again is not a good approach given the real-world needs
> of real-world applications.
>
> 5. Your ideas here.
#3 or add a flag to the clocksource which says 'frequency is guesswork' and
increase the threshold based on that.
If that flag is still set max_drift is != 0 after 20 seconds yell.
Thanks,
tglx
next prev parent reply other threads:[~2021-04-23 19:14 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 6:49 [clocksource] 6c52b5f3cf: stress-ng.opcode.ops_per_sec -14.4% regression kernel test robot
2021-04-20 13:43 ` Paul E. McKenney
2021-04-20 14:05 ` Paul E. McKenney
2021-04-21 6:07 ` [LKP] " Xing, Zhengjun
2021-04-21 13:42 ` Paul E. McKenney
2021-04-22 6:58 ` Xing Zhengjun
2021-04-22 7:41 ` Feng Tang
2021-04-22 14:24 ` Paul E. McKenney
2021-04-22 16:57 ` Paul E. McKenney
2021-04-23 6:11 ` Feng Tang
2021-04-23 14:02 ` Paul E. McKenney
2021-04-24 12:29 ` Feng Tang
2021-04-24 17:53 ` Paul E. McKenney
2021-04-25 2:14 ` Feng Tang
2021-04-25 3:14 ` Feng Tang
2021-04-25 19:15 ` Paul E. McKenney
2021-04-25 19:14 ` Paul E. McKenney
2021-04-26 12:39 ` Thomas Gleixner
2021-04-26 14:05 ` Feng Tang
2021-04-26 14:33 ` Thomas Gleixner
2021-04-26 15:12 ` Feng Tang
2021-04-23 2:15 ` Xing Zhengjun
2021-04-23 4:12 ` Paul E. McKenney
2021-04-23 19:14 ` Thomas Gleixner [this message]
2021-04-23 21:14 ` Paul E. McKenney
2021-04-23 23:39 ` Paul E. McKenney
2021-04-23 19:09 ` Thomas Gleixner
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