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From: Rodolfo Giometti <giometti@enneenne.com>
To: David Woodhouse <dwmw2@infradead.org>,
	Richard Cochran <richardcochran@gmail.com>,
	Andrew Lunn <andrew+netdev@lunn.ch>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	John Stultz <jstultz@google.com>,
	Thomas Gleixner <tglx@kernel.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Miroslav Lichvar <mlichvar@redhat.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Alexander Gordeev <agordeev@linux.ibm.com>
Subject: Re: [PATCH v4 2/4] pps: Drop the !NO_HZ_COMMON dependency from NTP_PPS
Date: Tue, 29 Sep 2026 08:33:40 +0200	[thread overview]
Message-ID: <decd5d05-1373-4ddc-95bc-46b73d6f6b99@enneenne.com> (raw)
In-Reply-To: <cb992b22907085c4ced8d9a35cd1c8836aad20ad.camel@infradead.org>

On Mon, 2026-09-28 at 20:28 +0100, David Woodhouse wrote:
> Yeah, working on that now. My first soak test on the nohz_full build
> didn't have nohz_idle, so it wasn't really very tickless.
[...]
> More data, and pretty graphs, when I'm confident of the results and have the
> A/B testing.

Thanks, looking forward to it.

For the A/B comparison, could you also report the hardpps side, i.e.
the PPS offset, jitter and stability as returned by adjtimex(), on
both the tickful and the tickless kernel? ntp_error shows that the
correction works; those show whether the PPS discipline converges as
well as it does today, which is what 2/4 is about.

Please also state whether the pulse comes from a real GPS on a GPIO
or from the vmclock 1PPS in 4/4.

> The ntp_error being corrected is still two orders of magnitude less
> than the jitter on the IRQ, mind you.

Worth a sentence in the commit message too, I think.

Ciao,

Rodolfo

  reply	other threads:[~2026-09-29  6:36 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-29 20:56 [PATCH v4 0/4] Add ntp_error to clock snapshot, enable NTP_PPS on tickless kernel David Woodhouse
2026-08-29 20:56 ` [PATCH v4 1/4] timekeeping: Apply extrapolated ntp_error to clock snapshots David Woodhouse
2026-08-29 20:57 ` [PATCH v4 2/4] pps: Drop the !NO_HZ_COMMON dependency from NTP_PPS David Woodhouse
2026-09-01 15:35   ` Rodolfo Giometti
2026-09-02  0:13     ` David Woodhouse
2026-09-28 13:37     ` David Woodhouse
2026-09-28 16:41       ` Rodolfo Giometti
2026-09-28 19:28         ` David Woodhouse
2026-09-29  6:33           ` Rodolfo Giometti [this message]
2026-09-29  9:32             ` David Woodhouse
2026-09-29 11:48               ` Rodolfo Giometti
2026-09-29 12:02                 ` David Woodhouse
2026-09-30  1:28                 ` David Woodhouse
2026-09-30 12:57                   ` Rodolfo Giometti
2026-09-30 10:37                 ` David Woodhouse
2026-09-30 12:57                   ` Rodolfo Giometti
2026-09-30 14:05                     ` David Woodhouse
2026-09-30 18:24                       ` David Woodhouse
2026-10-01  8:20                         ` Rodolfo Giometti
2026-10-01  9:08                           ` David Woodhouse
2026-08-29 20:57 ` [PATCH v4 3/4] pps: Always use ktime_get_snapshot_id() for pps_get_ts() David Woodhouse
2026-09-01 15:35   ` Rodolfo Giometti
2026-09-01 23:56     ` David Woodhouse
2026-09-26 20:38     ` David Woodhouse
2026-09-28  7:58       ` Rodolfo Giometti
2026-09-28 12:59         ` David Woodhouse
2026-09-28 16:41           ` Rodolfo Giometti
2026-10-01 13:14         ` Miroslav Lichvar
2026-10-01 15:38           ` David Woodhouse
2026-10-02  7:04           ` Rodolfo Giometti
2026-10-02  9:07             ` David Woodhouse
2026-10-02 12:29               ` David Woodhouse
2026-10-02 13:44                 ` David Woodhouse
2026-10-03 11:29                   ` David Woodhouse
2026-10-05  9:16                   ` Miroslav Lichvar
2026-08-29 20:57 ` [PATCH v4 4/4] [DO NOT MERGE] ptp: ptp_vmclock: Add simulated 1PPS support David Woodhouse
2026-09-01 15:35 ` [PATCH v4 0/4] Add ntp_error to clock snapshot, enable NTP_PPS on tickless kernel Rodolfo Giometti
2026-09-01 23:37   ` David Woodhouse

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