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Thu, 5 Feb 2026 12:12:35 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id aKqWWL6Za69u for ; Thu, 5 Feb 2026 12:12:34 +0000 (UTC) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=2a0a:51c0:0:12e:550::1; helo=galois.linutronix.de; envelope-from=bigeasy@linutronix.de; receiver= DMARC-Filter: OpenDMARC Filter v1.4.2 smtp1.osuosl.org 4BF7E84152 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 4BF7E84152 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by smtp1.osuosl.org (Postfix) with ESMTPS id 4BF7E84152 for ; Thu, 5 Feb 2026 12:12:34 +0000 (UTC) Date: Thu, 5 Feb 2026 13:12:29 +0100 From: Sebastian Andrzej Siewior To: Kurt Kanzenbach Message-ID: <20260205121229.AwxNfEl_@linutronix.de> References: <20260205-igb_irq_ts-v3-1-2efc7bc4b885@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260205-igb_irq_ts-v3-1-2efc7bc4b885@linutronix.de> X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1770293551; 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=7PelbcnS3xUMscOsvh2ZeX/gyBEvi2+xKP1rvNjD0C8=; b=ZQPf6a6yM+MN8oWcb8D/hbpJDAPU5eQClQGr/bAQeReS94O/EkUOlrrvm+Y5BQkFcE/Fin xsPHTaZLbJCrxVqYEH2qlXYPyy6y6vR7Jqg3GLgHHFbKuANwi/pQTK9ZH951Uc9xh3x54a r5jjdxcHJdZdAYDJ/U8QZ1akFmO9fNihVjG87eg4uXkR8d3pSSoUXe15kgrLhhDjm9ti3e udq4klY7jPgyfNuSK/DjCCyT2Aztzf+CmEIJdx2IXyFehCsCTLNTZrz1vcZrht7PwDUQnI kMLEaFNgdT+dCDunkdhaJ4pHmZ7rNMigRWl0GlqdYbOgTnO1LswqwDV6ShC7Mg== X-Mailman-Original-DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1770293551; 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=7PelbcnS3xUMscOsvh2ZeX/gyBEvi2+xKP1rvNjD0C8=; b=PgYUZHNktT88QYXXPu7EIYbh4Rp3lqX4vzxGT81vpxAupALs1NelX9ES3lsjbJXxZZmBC6 mm8buKh0B+D8XLAQ== X-Mailman-Original-Authentication-Results: smtp1.osuosl.org; dmarc=pass (p=none dis=none) header.from=linutronix.de X-Mailman-Original-Authentication-Results: smtp1.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=ZQPf6a6y; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=PgYUZHNk Subject: Re: [Intel-wired-lan] [PATCH iwl-next v3] igb: Retrieve Tx timestamp directly from interrupt for i210 X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paul Menzel , Vadim Fedorenko , Vinicius Costa Gomes , Przemek Kitszel , Richard Cochran , linux-kernel@vger.kernel.org, Andrew Lunn , Eric Dumazet , netdev@vger.kernel.org, Tony Nguyen , intel-wired-lan@lists.osuosl.org, Jacob Keller , Jakub Kicinski , Paolo Abeni , "David S. Miller" Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On 2026-02-05 08:54:34 [+0100], Kurt Kanzenbach wrote: > Retrieve Tx timestamp directly from interrupt handler for i210. > > 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. i210 is often used in > industrial systems, where timestamp timeouts can be fatal. > > Therefore, fetch the timestamp directly from the interrupt handler. > > The work queue code stays for all other NICs supported by igb. > > Tested on Intel i210 and i350. > > Signed-off-by: Kurt Kanzenbach Reviewed-by: Sebastian Andrzej Siewior IMHO this is a compromise with Miroslav where he observed less PTP timestamps on the i350. While testing I did not get near Miroslav's difference but there was a small change. I don't understand *why* because the current workqueue usage reads the timestamp on the same CPU on which the interrupt occurred. Doing it directly just avoids the context switch. This feels beneficial. Sebastian