From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6EBDD324B27; Tue, 3 Mar 2026 13:38:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772545108; cv=none; b=LJryFkBiDds2FZmxlxmQdGrtqgnGtgELYojvY6oxYjR45i2Vr3KmyuGoL8NH4UP77cAfRqNT8OqIipXPdavND0DH4ohMBkI+o+SYzJrPI+62m1iJ0tcmjPrfOUxi8tJ7mAD4uA/0tCGUELLekZPgzhnUSYegzqaobvlSY7cf2vA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772545108; c=relaxed/simple; bh=rDVzuxgJEXtCRZZ1xCN0kX1QxeN7h7mj0UkuWn4bbwc=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=UvFCb59EcWXiWl9jKlEfweULruI7+y6awR0P6ph2VZRRpp9yMoLmlZai74v7fQ7L3rN7+nX1sVpOIV+wVq/sJMsPTktX8U4BsWPjAWJWa2rnDAI2jdJqPFK5aIxjh7UGeoHr0g7BkvN+R3UCG75CGG18ExbsSYwb/w2rBwT73Gs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=4LDBZPmK; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=lBEyQk8P; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="4LDBZPmK"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="lBEyQk8P" From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1772545093; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rDVzuxgJEXtCRZZ1xCN0kX1QxeN7h7mj0UkuWn4bbwc=; b=4LDBZPmKYMrMkaPbCVywO2f3s+eYFA984rvFUndjVB18nt16AhKieNdKRpe8qkXfvl+ssE O8Dn79K94qr9J7P19d6iRQkBh2L9olhXM/vYKyFxqaTMiCXvaOKZybh7XE9pFRV751mS3H n9/gpb1zPzMQOMyUZ+m3YMZQqJkMK2JPiZ7Am3w2H73NhMyI7jesIoekiyfzvmeDo7tptE y0YNPrD+DaxThz0U5m8F//GOoOyNdBkY9eD0TBifQxYojVgBomqi08plios9MrESUFkwzX EnrqatylNbhsUO8s6RwrmQMVP+nvK6vJ06pZQZDqgicL1Bl26/PR4gjXrn6tEQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1772545093; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rDVzuxgJEXtCRZZ1xCN0kX1QxeN7h7mj0UkuWn4bbwc=; b=lBEyQk8PaGlnn48Bha/m0Iv1tc+mdAuXfNtqRyogmn0XZmB1fSdSfLl1MphKBw/Zxpsoxg i7nXcoi5WxknxtCg== To: Paul Menzel Cc: Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Richard Cochran , Vinicius Costa Gomes , Sebastian Andrzej Siewior , Vadim Fedorenko , Miroslav Lichvar , Jacob Keller , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH iwl-next v4] igb: Retrieve Tx timestamp from BH workqueue In-Reply-To: <9805389e-9ea4-4e7a-a122-65f733ead33c@molgen.mpg.de> References: <20260303-igb_irq_ts-v4-1-cbae7f127061@linutronix.de> <9805389e-9ea4-4e7a-a122-65f733ead33c@molgen.mpg.de> Date: Tue, 03 Mar 2026 14:38:11 +0100 Message-ID: <87qzq1rq2k.fsf@jax.kurt.home> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue Mar 03 2026, Paul Menzel wrote: > Dear Kurt, > > > Thank you for the patch. > > Am 03.03.26 um 12:48 schrieb Kurt Kanzenbach: >> Retrieve Tx timestamp from system BH instead of regular system workqueue. >>=20 >> The current implementation uses schedule_work() which is executed by the >> system work queue and kworkers to retrieve Tx timestamps. This increases >> latency and can lead to timeouts in case of heavy system load. i210 is >> often used in industrial systems, where timestamp timeouts can be fatal. >>=20 >> Therefore, switch to the system BH workqueues which are executed directly >> at the end of the IRQ handler. > > Thank you for implementing this. > >> Tested on Intel i210 and i350 with ptp4l. > > It would be great, if you shared the numbers. Did Miroslav already test=20 > this? Great question. I did test with ptp4l and synchronization looks fine < below 10ns back to back as expected. I did not test with ntpperf, because I was never able to reproduce the NTP regression to the same extent as Miroslav reported. Therefore, Miroslav is on Cc in case he wants to test it. Let's see. 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