From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 A685813A3F7; Sun, 5 Jul 2026 01:06:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783213574; cv=none; b=X/WZ3Kl/Vpx9cm7w1uC2bXMkOolVljXdcWTbNG2HGFMbxl8CLPagFwBQkHZLc7e5tPbet0Rit+IIbpOVfy040+u8Q/MmVxr0EUh0okwVsofrEEfPoSFOVpadmHggCdWZdhvMHUiA0xA3CXrcpOEbv866P2v/UL3FTK78AjMHJeI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783213574; c=relaxed/simple; bh=q3P4U4nKPKnQeDEGJEM8BsOP6yrOs+if7vZ3vvCi48E=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=flJBr8uDPOhBdOaSLl404jirHWSbJ/prXTRWywY1kJwINHf3m4X4J/WQBCumuPP3qkRke9gR1PMg2iArAPcrljfp1yQS4pPbvAk16TkvaYutpwwCrqyypb9Fvo6hmMolAnz+aJskmqIMQ3PQVxl34ZLS5vdUalYkcHdbHXT0PFc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=KFRAv1Ig; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="KFRAv1Ig" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C907B1F000E9; Sun, 5 Jul 2026 01:06:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783213572; bh=ft3r6NFcOCb3kuo8w3s9c+oIeiqaP3U/+EY0XOtwKdk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=KFRAv1Ig6Of8BNawkkN9VraBMiC9hBDjFDfTW6HpiHCiWZivUaA7a9wnMhxuRKpm4 Ydt8EILndaoE2G7VkjvLNg4fY9XMT10A+coB5s7aJDDnbowwSYf06asWsWr3fXA0dQ QMhVHGrVRNxYcDS+y08p9yX5KjzhgjcYrHL5Z9GE= Date: Sat, 4 Jul 2026 18:06:11 -0700 From: Andrew Morton To: Calvin Owens Cc: linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, Rodolfo Giometti , Sebastian Andrzej Siewior , 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: <20260704180611.8898a9e290016d2dda70f6ae@linux-foundation.org> In-Reply-To: <2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org> References: <2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 1 Jun 2026 17:44:09 -0700 Calvin Owens wrote: > 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. Thanks, I'll add this to mm.git's mm-nonmm-unstable branch. This means it will get linux-next exposure immediately. All being well, I'll later move this into the non-rebasing mm-nonmm-stable branch with the intent to upstream it in the next merge window. Sashiko AI review might have found some issues, one of them pre-existing. Please check it out: https://sashiko.dev/#/patchset/2e32729029fbf6977ecf04665eb00f2efd3e2c17.1780359378.git.calvin@wbinvd.org