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 DA1871863E for ; Tue, 19 Aug 2025 06:09:28 +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=1755583770; cv=none; b=OsxdMuIjxNCr/phm+5T8xSEnYhsXN8D+Jij1EntAci2lqP6s5rhoIeBKbNRiO1trrwFgLhC059kfo7n2tiTz/2lbqs+3/v2NjAhYaE1D7hl5whtbU7WHxzc5Uxv2ZjAwLDWj5KGIqb9kS3A3mgegUONFV8UX2ysquVzmdIw1wuI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755583770; c=relaxed/simple; bh=rL+TrUW6tiyvddHWQRgJrjB30uAutfdbI4yIw0BN8hQ=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=J2h2MVzmVuaygC3NnHD0Dpt9AQ3EoNSSHcaDKmkssGnz3snZGo0fyUcJkiISnfktnm8RFYdAQVSYFyeukt26fgoZzV1l6le0LYtVm8RUGVpAY/QFNGU8H82WzGLcrRXnLMi5/QTm+grjql0LNyIStX6J3QXXMyC0qDzysWqwy6k= 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=ZGCq7qCf; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=SdkPN5lA; 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="ZGCq7qCf"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SdkPN5lA" From: Kurt Kanzenbach DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1755583766; 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=rL+TrUW6tiyvddHWQRgJrjB30uAutfdbI4yIw0BN8hQ=; b=ZGCq7qCfzC5H3GygyPZRbiTCwyFLWcjdY2GuCVTSeKzsFHLFi7TnN2rA4bRkAEQYHEWwx2 Sfa9Xe29n0OaffTVuC9J6MUc67waFR1yW/pkPD6SAYohfACHVFENHKtoFJUj3Tw1jwJWC0 8AYmBdbwddYzJ0w6lzjwNX07k/tMJrnsyulDzM8WbTMqCmUXTihkn+dQK6hLAb8sZ9V3Ax lVnVn14sqyaxE+72Iw7hO6am1JCWDyRrJdihxn8jcTxYsCZm0sf5bWue+IFqtBvic41CgV ChDG7IP/Ijw6260Hi/ammf/N/MVPo9J3DnLZTDrsaosc892S5+FbG5nupgmt9g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1755583766; 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=rL+TrUW6tiyvddHWQRgJrjB30uAutfdbI4yIw0BN8hQ=; b=SdkPN5lASqNdoU8R88W/4y657SDrKUFPVaiX6qrGSBu6g8zZKUVSj7+sEnbKFPZte733Tl zP6HS2zQ2xQOF9Ag== To: Miroslav Lichvar Cc: Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Richard Cochran , Vinicius Costa Gomes , Sebastian Andrzej Siewior , intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org Subject: Re: [Intel-wired-lan] [PATCH iwl-next] igb: Retrieve Tx timestamp directly from interrupt In-Reply-To: References: <20250815-igb_irq_ts-v1-1-8c6fc0353422@linutronix.de> Date: Tue, 19 Aug 2025 08:09:25 +0200 Message-ID: <87y0rf4zca.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 Mon Aug 18 2025, Miroslav Lichvar wrote: > On Fri, Aug 15, 2025 at 08:50:23AM +0200, Kurt Kanzenbach wrote: >> Retrieve Tx timestamp directly from interrupt handler. >>=20 >> The current implementation uses schedule_work() which is executed by the >> system work queue to retrieve Tx timestamps. This increases latency and = can >> lead to timeouts in case of heavy system load. >>=20 >> Therefore, fetch the timestamp directly from the interrupt handler. >>=20 >> The work queue code stays for the Intel 82576. Tested on Intel i210. > > I tested this patch on 6.17-rc1 with an Intel I350 card on a NTP > server (chrony 4.4), measuring packet rates and TX timestamp accuracy > with ntpperf. While the HW TX timestamping seems more reliable at some > lower request rates, there seems to be about 40% drop in the overall > performance of the server in how much requests it can handle (falling > back to SW timestamps when HW timestamp is missed). Is this expected > or something to be considered?=20 Thanks for testing! Nope, this is not really expected. Let me see if I can reproduce your results and see where that comes from. 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