Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934998AbeAKQio (ORCPT + 1 other); Thu, 11 Jan 2018 11:38:44 -0500 Received: from shards.monkeyblade.net ([184.105.139.130]:39728 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934499AbeAKQin (ORCPT ); Thu, 11 Jan 2018 11:38:43 -0500 Date: Thu, 11 Jan 2018 11:38:40 -0500 (EST) Message-Id: <20180111.113840.1908989919518121712.davem@davemloft.net> To: peterz@infradead.org Cc: edumazet@google.com, dima@arista.com, frederic@kernel.org, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com, akpm@linux-foundation.org, fweisbec@gmail.com, hannes@stressinduktion.org, mingo@kernel.org, alexander.levin@verizon.com, pabeni@redhat.com, paulmck@linux.vnet.ibm.com, rrendec@arista.com, riel@redhat.com, sgruszka@redhat.com, tglx@linutronix.de, wanpeng.li@hotmail.com Subject: Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context From: David Miller In-Reply-To: <20180111163204.GE6176@hirez.programming.kicks-ass.net> References: <1515681091.3039.21.camel@arista.com> <20180111163204.GE6176@hirez.programming.kicks-ass.net> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 11 Jan 2018 08:38:42 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Peter Zijlstra Date: Thu, 11 Jan 2018 17:32:04 +0100 > You just introduced a 2ms preempt-disable region I think, that's not > cool for PREEMPT and a plain bug on PREEMPT_RT. I'd just like to know what the difference is between ksoftirqd running softirq work for 2ms and the real softirq context doing it. The latter already has this "2ms preempt-disable region" of sorts, right?