From: Miroslav Lichvar <mlichvar@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
John Stultz <john.stultz@linaro.org>,
Prarit Bhargava <prarit@redhat.com>,
Alessandro Zummo <a.zummo@towertech.it>,
linux-rtc@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch 5/8] ntp: Make the RTC synchronization more reliable
Date: Mon, 7 Dec 2020 13:47:49 +0100 [thread overview]
Message-ID: <20201207124749.GH2352378@localhost> (raw)
In-Reply-To: <20201206220542.062910520@linutronix.de>
On Sun, Dec 06, 2020 at 10:46:18PM +0100, Thomas Gleixner wrote:
> Switch it to an hrtimer instead which schedules the actual update work. The
> hrtimer will expire precisely (max 1 jiffie delay when high resolution
> timers are not available). The actual scheduling delay of the work is the
> same as before.
It works well in my tests.
> This becomes now:
>
> if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer))
> queue_work(system_power_efficient_wq, &sync_work, 0);
>
> which is racy when the hrtimer has expired and the work is currently
> executed and has not yet managed to rearm the hrtimer.
>
> Not a big problem as it just schedules work for nothing.
No more unexpected updates of the RTC observed.
Tested-by: Miroslav Lichvar <mlichvar@redhat.com>
Thanks,
--
Miroslav Lichvar
next prev parent reply other threads:[~2020-12-07 12:49 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-06 21:46 [patch 0/8] ntp/rtc: Fixes and cleanups Thomas Gleixner
2020-12-06 21:46 ` [patch 1/8] rtc: mc146818: Prevent reading garbage Thomas Gleixner
2021-01-25 18:40 ` [patch 1/8] rtc: mc146818: Prevent reading garbage - bug Mickaël Salaün
2021-01-26 13:26 ` Thomas Gleixner
2021-01-26 14:17 ` Mickaël Salaün
2021-01-26 15:35 ` Thomas Gleixner
2021-01-26 17:02 ` [PATCH V2] rtc: mc146818: Detect and handle broken RTCs Thomas Gleixner
2021-01-26 18:00 ` Alexandre Belloni
2021-01-31 10:59 ` Dirk Gouders
2021-02-01 13:53 ` Serge Belyshev
2021-02-01 19:09 ` [PATCH] rtc: mc146818: Dont test for bit 0-5 in Register D Thomas Gleixner
2021-02-01 19:24 ` [PATCH V2] " Thomas Gleixner
2021-02-01 19:32 ` Linus Torvalds
2021-02-01 19:40 ` Thomas Gleixner
2021-02-11 23:09 ` Maciej W. Rozycki
2021-02-01 19:38 ` Alexandre Belloni
2021-02-01 20:09 ` Borislav Petkov
2021-02-01 20:15 ` Dirk Gouders
2021-02-02 4:22 ` Len Brown
2021-02-03 13:00 ` Mickaël Salaün
2020-12-06 21:46 ` [patch 2/8] rtc: mc146818: Reduce spinlock section in mc146818_set_time() Thomas Gleixner
2020-12-06 21:46 ` [patch 3/8] rtc: cmos: Make rtc_cmos sync offset correct Thomas Gleixner
2020-12-07 20:50 ` Jason Gunthorpe
2020-12-06 21:46 ` [patch 4/8] rtc: core: Make the sync offset default more realistic Thomas Gleixner
2020-12-07 20:55 ` Jason Gunthorpe
2020-12-10 23:59 ` Alexandre Belloni
2020-12-11 0:23 ` Thomas Gleixner
2020-12-11 0:28 ` Alexandre Belloni
2020-12-06 21:46 ` [patch 5/8] ntp: Make the RTC synchronization more reliable Thomas Gleixner
2020-12-07 12:47 ` Miroslav Lichvar [this message]
2020-12-07 20:59 ` Jason Gunthorpe
2020-12-29 19:41 ` Geert Uytterhoeven
2021-01-11 10:12 ` Thomas Gleixner
2021-01-11 10:40 ` Geert Uytterhoeven
2020-12-06 21:46 ` [patch 6/8] ntp, rtc: Move rtc_set_ntp_time() to ntp code Thomas Gleixner
2020-12-07 20:59 ` Jason Gunthorpe
2020-12-09 3:51 ` Alexandre Belloni
2020-12-06 21:46 ` [patch 7/8] ntp: Make the RTC sync offset less obscure Thomas Gleixner
2020-12-06 21:46 ` [patch 8/8] ntp: Consolidate the RTC update implementation Thomas Gleixner
2020-12-07 21:05 ` Jason Gunthorpe
2020-12-11 9:23 ` Thomas Gleixner
2020-12-09 0:33 ` [patch 0/8] ntp/rtc: Fixes and cleanups Thomas Gleixner
2020-12-09 4:01 ` Alexandre Belloni
2020-12-09 12:39 ` Thomas Gleixner
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