linux-kernel - Re: [Intel-wired-lan] [PATCH iwl-next v3] igb: Retrieve Tx timestamp directly from interrupt for i210

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Message-ID: <20260211134436.1e623034@kernel.org>
Date: Wed, 11 Feb 2026 13:44:36 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Jacob Keller <jacob.e.keller@...el.com>
Cc: Kurt Kanzenbach <kurt@...utronix.de>, Willem de Bruijn
 <willemdebruijn.kernel@...il.com>, Sebastian Andrzej Siewior
 <bigeasy@...utronix.de>, Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
 Willem de Bruijn <willemb@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
 Eric Dumazet <edumazet@...gle.com>, "David S. Miller"
 <davem@...emloft.net>, "Loktionov, Aleksandr"
 <aleksandr.loktionov@...el.com>, "Nguyen, Anthony L"
 <anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
 <przemyslaw.kitszel@...el.com>, Paul Menzel <pmenzel@...gen.mpg.de>,
 "Gomes, Vinicius" <vinicius.gomes@...el.com>, "netdev@...r.kernel.org"
 <netdev@...r.kernel.org>, Richard Cochran <richardcochran@...il.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Lunn
 <andrew+netdev@...n.ch>, "intel-wired-lan@...ts.osuosl.org"
 <intel-wired-lan@...ts.osuosl.org>
Subject: Re: [Intel-wired-lan] [PATCH iwl-next v3] igb: Retrieve Tx
 timestamp directly from interrupt for i210

On Wed, 11 Feb 2026 11:29:03 -0800 Jacob Keller wrote:
> > Moving the timestamping in IRQ looked like a good solution, because the
> > device already signals that the Tx timestamp is available now. No need
> > to schedule any worker/work at all. So, it'd be very nice if
> > skb_tstamp_tx() could be called from IRQ context. BTW other drivers like
> > igc call this function in IRQ context as well.
> 
> Right. Reporting the timestamp from the interrupt is the simplest and 
> lowest latency method. I know Miroslav had some situations and devices 
> where it apparently caused more problems than it helped, though I don't 
> believe anyone else has reproduced those?

There's a BH workqueue now, as a replacement for tasklets.
Presumably smallest fix would be to switch to that?