From: Richard Cochran <richardcochran@gmail.com>
To: Miroslav Lichvar <mlichvar@redhat.com>
Cc: netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
Jacob Keller <jacob.e.keller@intel.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 net] igb: shorten maximum PHC timecounter update interval
Date: Tue, 30 Oct 2018 19:30:56 -0700 [thread overview]
Message-ID: <20181031023056.zqb5zl3wgl5fbbju@localhost> (raw)
In-Reply-To: <20181026171300.12720-1-mlichvar@redhat.com>
On Fri, Oct 26, 2018 at 07:13:00PM +0200, Miroslav Lichvar wrote:
> The timecounter needs to be updated at least once per ~550 seconds in
> order to avoid a 40-bit SYSTIM timestamp to be misinterpreted as an old
> timestamp.
>
> Since commit 500462a9de65 ("timers: Switch to a non-cascading wheel"),
> scheduling of delayed work seems to be less accurate and a requested
> delay of 540 seconds may actually be longer than 550 seconds. Also, the
> PHC may be adjusted to run up to 6% faster than real time and the system
> clock up to 10% slower. Shorten the delay to 360 seconds to be sure the
> timecounter is updated in time.
>
> This fixes an issue with HW timestamps on 82580/I350/I354 being off by
> ~1100 seconds for few seconds every ~9 minutes.
Acked-by: Richard Cochran <richardcochran@gmail.com>
next prev parent reply other threads:[~2018-10-31 11:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-26 17:13 [PATCH v2 net] igb: shorten maximum PHC timecounter update interval Miroslav Lichvar
2018-10-26 17:20 ` Keller, Jacob E
2018-10-31 2:30 ` Richard Cochran [this message]
2018-11-03 1:06 ` [Intel-wired-lan] " Brown, Aaron F
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