From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D41FBC4338F for ; Mon, 23 Aug 2021 07:44:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFF2360F3A for ; Mon, 23 Aug 2021 07:44:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235147AbhHWHpG (ORCPT ); Mon, 23 Aug 2021 03:45:06 -0400 Received: from mout.gmx.net ([212.227.15.19]:38733 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234940AbhHWHpD (ORCPT ); Mon, 23 Aug 2021 03:45:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1629704641; bh=vdU4SqHf7ge2RbpNt68iHCwDufd72LRd0wLyAczRbDQ=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=HpuRqLSgr4yOerjCm8hW/7ydeCgfoqj2dPW/7WJV3pHnlT3lZR/7R6pA4bnqjb7o5 0vulaVZ2Y1pTR1nTldYqlaB3/EtdvlZFC5eBbtML1XoRKn8aP4tyKBU7Z0B2pPRmFe tX7LqKZRxbCTMq2hu1wzDGF1sUv8YEgrP7gNbiWU= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([212.114.172.232]) by mail.gmx.net (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1Mz9Un-1nCUrr3EFH-00wHM0; Mon, 23 Aug 2021 09:44:00 +0200 Message-ID: <275a0f09654cf5644cbc5731fa031b218eed6d38.camel@gmx.de> Subject: Re: Re: [PATCH,RESEND] softirq: Introduce SOFTIRQ_FORCED_THREADING From: Mike Galbraith To: =?UTF-8?Q?=E7=8E=8B=E6=93=8E?= Cc: Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Frederic Weisbecker , Michal Hocko , Davidlohr Bueso , Will Deacon , "Paul E. McKenney" , Dirk Behme , linux-kernel@vger.kernel.org Date: Mon, 23 Aug 2021 09:43:58 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.40.3 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:q7hWs4qhhqDoSey/6ghUiouWmoWiRLD6tLJi3s1a3JLbRFEGhe7 X2hnmBYEZ+2FpwugEEbpA3S1gIktQDM1aODpqwuFNmtSbROVKuFbXxaNRUyke++dXSlxBKQ y9XPjqo66TCHg1eM7ONFUzNtBbYE0qOnde22jGRYVh1391SkRKvxPJKYrt/9TJVLqxK3aSW m4x9BG/zR1j/P/y84hH+A== X-UI-Out-Filterresults: notjunk:1;V03:K0:+w53KnWJzrc=:2nVmY3KDPm1fE7n1JneFDN JjWAiGDZj/adnm1/gXmek4ACcoCBWaXicjpuFYa4LWCD+z/dBQfEhguzyi2Jhy2Rw2/3M77yt Xxq7B8Pm3YJiCGNiDGaHyoFFQo2lpL+3/ybAFEmEXQHjo3R7FuJiQd3G6g5FNNI1z3NCUWIWQ D8pCVnmvGKiOvcJNHCtwmdKlRuG79ZmX2gkJUBefBS5A9xsyLfwZ8/aPkcQXZHHMuR6pN30pA VzrW86v8X0EZhSCn4nXESdErmHCZI1CPSP1sZWRDgleu8rLzugvlu/2aeiqmeWTuZrVeT9WX5 vOB4j0APPOi+JYipxgzKRurV5PGBa+vmqT1550Sr5qwtji8PezKj7W+IlccPKNzbJIo0eBAoF B50/q6DLX8qMFINbZZJSMpOny9zYw3JjJumnMon3GktoDPsjYCMB8V0eJF3pd2GZqJvVKaosa zG3nU5Yet1W5kH3dtOsinCz4th0E5dIYzDDTu9SX0aYizJ+Ip2fK8ntwFVmeDpNjtCiHYAbrQ A/6iDshtv3yywym9ldyMYdaxkWC80duddaCbYPmNNIQJH255Zj1u+cXiytvKaoJ6sny76PKm9 cjU1iaPSnFOV4jGVUybpIn4SoFRjuexmrGu7wsLcXSkR4qdkaFchLVVqdi0MjucLe6Y4NfUOa rE+f6yrtrQzgnp+kqbZV9vFfeqct7oZ4MLLxYvnTL96TqMvWn3hxRzbiSgTMh2k2wKctFoUSi KyMmzbkaDE3XUpikmHxQE13LVSVXZXeyLPZ5vuTZTsZIfOm14nfBMzl1SC13H7NN4VSVeBNYS TSlg1jOsc3xeFEJ30dpdC5iln9ixfIw356MM+dQg+YGM2zCuKZIHYzuiQn12vTOl8KJPYG79V xWoglWRjCZrThkPil3jjobJklV/+bKjI1GhgfK9s1CLZx0DcKV0l/+UbAhYLCO5g6X4ncEEki dm0Cw/QYn/HEWBOiomIGznO9BuWXd7cbWG8NhbAbTJciUIWNK19Or2YH+Oo0p6PnQiZ4EwH0s QkYJA04rXePKSw9mdervOZPa79G5SKhMCISiMCJY2WAkBLfNkVoGA73AZEegS9wiI2/qn9abW 8ERwaM/St7QXtmQSS7nyxrCDihnkaSSCVlQ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2021-08-23 at 14:33 +0800, =E7=8E=8B=E6=93=8E wrote: > > > On Mon, 2021-08-23 at 11:33 +0800, Wang Qing wrote: > > > At present, whether the softirq is executed when the interrupt exits > > > is controlled by IRQ_FORCED_THREADING. This is unreasonable. It shou= ld > > > be split and allowed to take effect separately. > > > > Decades long practice suddenly became "unreasonable"?=C2=A0 I think no= t. =C2=A0 > > "unreasonable" may be my misnomer, but it is really necessary to separat= e > softirq from IRQ_FORCED_THREADING, which can be effective separately. Well, no, it's not necessary, but would be damn convenient to you, which is of course a perfectly fine motivation to post a patch :) > > > > Trying to carve out bits and pieces of RT to merge immediately isn't > > likely to make the ongoing merge effort go anyfaster or smoother. > > I am not trying to carve out bits and pieces of RT, but I encountered ac= tual > problems in my project. For example, in Android, we will not enable > IRQ_FORCED_THREADING, Android is not a high real-time requirements, > but in some scenariossome, RT processes cannot be scheduled in time > and the frame is dropped due to the execution time of softirq is too lon= g, > also some softirq cannot be executed in time in ksoftirqs, and delays oc= cur, > such as IO. That didn't parse well here. What you seem to be saying is that you have a hard constraint that can't be meet, yet are unwilling to use an existing facility to resolve that issue because the kernel you're using is not _intended_ to support hard realtime... therefore you want this other facility to enable it to support your hard realtime requirement. That can't be right, but it doesn't really matter, because... > Therefore, why not give the user a choice to balance the execution of so= ftirq > while not enable IRQ_FORCED_THREADING, so as to meet the inconsistent > scenes and needs ...it's not my call, I just found the language rather odd. It still looks to me like you're carving out a slice of RT. -Mike