netdev - Re: [PATCH iwl-next v2] igb: Convert Tx timestamping to PTP aux worker

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Message-ID: <aK8OrXDsZclpSQzF@localhost>
Date: Wed, 27 Aug 2025 15:57:01 +0200
From: Miroslav Lichvar <mlichvar@...hat.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Jacob Keller <jacob.e.keller@...el.com>,
	Kurt Kanzenbach <kurt@...utronix.de>,
	Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Richard Cochran <richardcochran@...il.com>,
	Vinicius Costa Gomes <vinicius.gomes@...el.com>,
	Paul Menzel <pmenzel@...gen.mpg.de>,
	Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org
Subject: Re: [PATCH iwl-next v2] igb: Convert Tx timestamping to PTP aux
 worker

On Tue, Aug 26, 2025 at 02:59:12PM +0200, Sebastian Andrzej Siewior wrote:
> The benchmark is about > 1k packets/ second while in reality you have
> less than 20 packets a second.

I don't want to argue about which use case is more important, but it's
normal for NTP servers to receive requests at much higher rates than
that. In some countries, public servers get hundreds of thousands of
packets per second. A server in a local network may have clients
polling 128 times per second each.

Anyway, if anyone is still interested in finding out the cause of
the regression, there is a thing I forgot to mention for the
reproducer using ntpperf. chronyd needs to be configured with a larger
clientloglimit (e.g. clientloglimit 100000000), otherwise it won't be
able to respond to the large number of clients in interleaved mode
with a HW TX timestamp. The chronyc serverstats report would show
that. It should look like the outputs I posted here before.

-- 
Miroslav Lichvar