From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Subject: Re: Softirq priority inversion from "softirq: reduce latencies" Date: Mon, 07 Mar 2016 18:06:30 +0100 Message-ID: <1457370390.3635.6.camel@gmail.com> References: <56D1E8B6.6090003@hurleysoftware.com> <1456638957.3676.12.camel@gmail.com> <20160228170109.GA16322@electric-eye.fr.zoreil.com> <1456721889.3488.67.camel@gmail.com> <56DD9EE8.1010909@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Peter Hurley , Eric Dumazet , David Miller , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Greg KH , dmaengine@vger.kernel.org, John Ogness , Andrew Morton To: Sebastian Andrzej Siewior , Francois Romieu Return-path: Received: from mail-wm0-f51.google.com ([74.125.82.51]:33988 "EHLO mail-wm0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752697AbcCGRGf (ORCPT ); Mon, 7 Mar 2016 12:06:35 -0500 In-Reply-To: <56DD9EE8.1010909@linutronix.de> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2016-03-07 at 16:31 +0100, Sebastian Andrzej Siewior wrote: > On 02/29/2016 05:58 AM, Mike Galbraith wrote: > > WRT -rt: if dma tasklets really do have hard (ish) constraints, -rt > > recently "broke" in the same way.. of all softirqs which are deferred > > to kthread context, due to a recent change, only timer/hrtimer are > > executed at realtime priority by default. > > no. All softirqs are invoked in the context of the current process that > triggerd the softirq invocation. If NAPI goes on for too long (or other > softirq can't be executed in this context) it will continue in the > ksoftirqd. And this threads runs at a normal priority like it does in > mainline. > I adjusted it with mainline. Yeah, that's what I said, the ksoftirqd case became the same in -rt. -Mike