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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Peter Zijlstra <peterz@infradead.org>, tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, diego.viola@gmail.com,
	len.brown@intel.com, rui.zhang@intel.com
Subject: Re: [PATCH v2 0/7] Various tsc/clocksource fixes
Date: Tue, 01 May 2018 11:12:03 +0200	[thread overview]
Message-ID: <2748619.xuzImzcDij@aspire.rjw.lan> (raw)
In-Reply-To: <20180430100008.503783478@infradead.org>

On Monday, April 30, 2018 12:00:08 PM CEST Peter Zijlstra wrote:
> These patches are the result of the regression Diego reported against commit:
> 
>   aa83c45762a2 ("x86/tsc: Introduce early tsc clocksource")
> 
> His Core2 triggers mark_tsc_unstable() while we're running with tsc-early,
> which then results in us failing to unregister the clocksource.
> 
> Furthermore, since mark_tsc_unstable() only looks at the regular tsc
> clocksource, we don't even mark tsc_early UNSTABLE or de-rate it, resulting in
> it actually staying a desirable clocksource.
> 
> Fixing that is a little more tricky; albeit far less critical after we
> guarantee to unregister tsc-early.
> 
> Please consider these for /urgent. I've used both Fixes and stable tags
> on a bunch of them because the above commit is already in v4.16 and
> would need stable help.
> 
> These patches have been tested on both a Core2 and an IVB. On IVB I've both
> changed intel_idle to always report the TSC unstable and mucked about with the
> TSC msr from userspace to tickle the watchdog paths.
> 
> ---
> Changes since v1
> 
>  - fix __clocksource_change_rating() locking
>  - removed work->kthread->watchdog hoops
>  - fixed up comment
> 
> 

I've had a deeper look at the patches and have not found anything of concern
in them, so for the whole series:

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

      parent reply	other threads:[~2018-05-01  9:12 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 10:00 [PATCH v2 0/7] Various tsc/clocksource fixes Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 1/7] x86,tsc: Always unregister clocksource_tsc_early Peter Zijlstra
2018-05-02 14:12   ` [tip:timers/urgent] x86/tsc: " tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 2/7] clocksource: Allow clocksource_mark_unstable() on unregisered clocksources Peter Zijlstra
2018-05-02 13:35   ` Thomas Gleixner
2018-05-02 13:53     ` Peter Zijlstra
2018-05-02 14:13       ` [tip:timers/urgent] clocksource: Allow clocksource_mark_unstable() on unregistered clocksources tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 3/7] clocksource: Initialize cs->wd_list Peter Zijlstra
2018-05-02 13:37   ` Thomas Gleixner
2018-05-02 13:55     ` Peter Zijlstra
2018-05-02 14:13   ` [tip:timers/urgent] " tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 4/7] x86,tsc: Fix mark_tsc_unstable() Peter Zijlstra
2018-05-02 14:14   ` [tip:timers/urgent] x86/tsc: " tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 5/7] clocksource: Consistent de-rate when marking unstable Peter Zijlstra
2018-05-02 14:14   ` [tip:timers/urgent] " tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 6/7] clocksource: Rework stale comment Peter Zijlstra
2018-05-02 14:15   ` [tip:timers/urgent] " tip-bot for Peter Zijlstra
2018-04-30 10:00 ` [PATCH v2 7/7] clocksource: Remove kthread Peter Zijlstra
2018-05-02 14:42   ` [tip:timers/core] " tip-bot for Peter Zijlstra
2018-05-01  9:12 ` Rafael J. Wysocki [this message]

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