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 55E8D392C39 for ; Tue, 2 Jun 2026 06:36:53 +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=1780382215; cv=none; b=W5djDKyPf23iVkUXXJF/7XUV0TJ/V01iETqf48e7JIEBVBiRO6lAFONyTRb1eA2N396PO/BUOc5o6hNpUsesoqkTfB439SaL+mFDbgNagyKxy66t+KGoodxN+hXdTK7Z//XGe7i4z0X1VdhgiwjwIDtk5ED/gw2y2UaTzLDCUcg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780382215; c=relaxed/simple; bh=uN2KLYfWe4/29fI1yyckzMO9Lym1DS4Z7QZVgj9g+5A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=H+8jhI3xFKz9xYjprkEVugI9HsZ78vVCqk/7gTEOxEb21EcQjFRer4nS7qMRDAwJTREE7HORuqdSY15oFd2jLodDd/3s3MLYme5bzyVsUEX0exFAr2VmaAsVul7FmmIrzJDA16+bgpb0QYZYFqCMs3FkQ0Htm1LsoL8bAtBKaHk= 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=LGU9wEcv; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=XVNQH8sg; 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="LGU9wEcv"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="XVNQH8sg" Date: Tue, 2 Jun 2026 08:36:50 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1780382211; 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=8ZSsvRsfJqlkrFBLO1/Int2sfDx4YeIQ8CEnym8UuY8=; b=LGU9wEcvZgmh49lq0Ih4nyUrm4SEFQ3QPjN0AyiUHRSpdLo+Z9xhjJUx6hoE91VyuIsCRD XADqryeO97HuKVLaSX6NNXrEwC9woWhzu+TpeAUv8NXsrd4N7xpTnpqpIxVjEW3yvZCcsf t/rM90cxqlz2CWbkKE8kY+2jJCmz/ibGfXX4AK/bH17Ho7tc3skTKBZyTavUtJjapZIeUN kgksACuWgSyvcRoxnXFwFo7WlwMlL/5GNXopiBSDEcL5wQ9EQeCy7G1xUFbILg5fFDeqBY lpC2MuulbitSSxDyWnC27YkLZfvkGVwC4CVisC2esHSh9e/9vBQ6gCcsoFWQdw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1780382211; 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=8ZSsvRsfJqlkrFBLO1/Int2sfDx4YeIQ8CEnym8UuY8=; b=XVNQH8sgVtfYFFl/3saLdnaVj395BGbsPlx7nuQ5/RFxFZCWwdmGmyPDzh4Te96EuC9Pxa 2g6nAtmmTUMrLkAQ== From: Sebastian Andrzej Siewior To: Calvin Owens Cc: linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Rodolfo Giometti , Clark Williams , Steven Rostedt , Greg Kroah-Hartman , Eliav Farber , Michael Byczkowski , Ingo Molnar , David Laight , Thomas Gleixner Subject: Re: [PATCH v7 1/1] pps: pps-gpio: split IRQ handler into hardirq timestamper + threaded handler Message-ID: <20260602063650.LWatIBPk@linutronix.de> References: <2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org> Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org> On 2026-06-01 17:44:09 [-0700], Calvin Owens wrote: > From: Michael Byczkowski > > Split the pps-gpio interrupt handler into a primary (hardirq) handler > that captures the PPS timestamp at interrupt entry, and a threaded > handler that processes the event. This produces the same two-part > handler structure on both PREEMPT_RT and non-RT kernels. > > On non-RT kernels the threaded portion runs immediately after the > primary, with no behavioral change compared to the previous > single-handler implementation. > > On PREEMPT_RT, where interrupt handlers are force-threaded by default, > the previous single-handler implementation captured the timestamp > inside the threaded portion, after IRQ-thread scheduling delay. With > the split, the timestamp is captured in true hardirq context as it is > on non-RT kernels, eliminating a significant source of PPS jitter on > RT systems. > > Tested-by: Michael Byczkowski > Tested-by: Calvin Owens > Acked-by: Rodolfo Giometti > Signed-off-by: Michael Byczkowski > Signed-off-by: Calvin Owens > --- Reviewed-by: Sebastian Andrzej Siewior Sebastian