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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4608EC04A95 for ; Sat, 22 Oct 2022 18:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229583AbiJVSen (ORCPT ); Sat, 22 Oct 2022 14:34:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58126 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229850AbiJVSel (ORCPT ); Sat, 22 Oct 2022 14:34:41 -0400 Received: from mail-qv1-xf33.google.com (mail-qv1-xf33.google.com [IPv6:2607:f8b0:4864:20::f33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F02C1F9E5 for ; Sat, 22 Oct 2022 11:34:39 -0700 (PDT) Received: by mail-qv1-xf33.google.com with SMTP id x15so4053238qvp.1 for ; Sat, 22 Oct 2022 11:34:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=1e95uf0VzIyXTP1nwyIENyrVuUu1bwwXuPdhByZMPJM=; b=ugLhfbDMIgcuwCDeYy9cMtlJzCyjM8bnlZzIZ2Fyon/UUb6zbsAqGKz1ARs4QNJzJN 6f5kyfiFVSBg+hgOoX/LFAKk812AJ7n/XmK4+aQXWy8mu07eXMTxSys2U3wVHRXXrHXn 34rdBBfB44W7WtcnW/BlNPFs3MV3KziWtXH9c= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=1e95uf0VzIyXTP1nwyIENyrVuUu1bwwXuPdhByZMPJM=; b=RKqjlVTxTUFPvrhROIsZTW+oXM5K5G9ma6/eLXsbVx/wi2e/rYjPyXmoPU5bsWTBld zoCrs3kpjxiS985lekeYJib52ItFzvXdlonaBwgBmSNHTOVMB98V1UzUVY4f5LD122yM VURZ/iwTm/YwHRoNN40FFBaqEYGtlq5vwrkHvLhmN+tus4kxhVou+LsTfRdL8H04Ebfv JytGj916yhY1Q+sO08Emr31+vQgshNNFMSGYo33QobCm8J3Ayg5umjUQZDiQxlj7OIyB e9pRKRD024ZvfkYIugldboVB/guXOUQEy7sb0F9VBU8JD9923HBm7epDkgdb5qGVKnWs M0cg== X-Gm-Message-State: ACrzQf1H1E5E6Zou8D3HA6YXvM39d68g9SH8vktUbO9ziuhLqd7E2MyH 2dnA1Kcj9yrRypCAzK9OBmf1SA== X-Google-Smtp-Source: AMsMyM67wiEibEuUjzyqH0f0gdHtfWI/O0UjXckudpmGJa/qw/NWFgqZJCS4dbAxSSyKiL7yeYSyyA== X-Received: by 2002:a05:6214:2aa4:b0:4b3:fcfb:6479 with SMTP id js4-20020a0562142aa400b004b3fcfb6479mr21715985qvb.127.1666463678334; Sat, 22 Oct 2022 11:34:38 -0700 (PDT) Received: from localhost (228.221.150.34.bc.googleusercontent.com. [34.150.221.228]) by smtp.gmail.com with ESMTPSA id b1-20020ac87fc1000000b0039cc47752casm10502456qtk.77.2022.10.22.11.34.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 22 Oct 2022 11:34:37 -0700 (PDT) Date: Sat, 22 Oct 2022 18:34:37 +0000 From: Joel Fernandes To: Alexander Gordeev Cc: John Stultz , LKML , Connor O'Brien , John Dias , Rick Yiu , John Kacur , Qais Yousef , Chris Redpath , Abhijeet Dharmapurikar , Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Thomas Gleixner , kernel-team@android.com, "J . Avila" Subject: Re: [PATCH RFC v4 2/3] sched: Avoid placing RT threads on cores handling long softirqs Message-ID: References: <20221003232033.3404802-1-jstultz@google.com> <20221003232033.3404802-3-jstultz@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 20, 2022 at 02:47:54PM +0200, Alexander Gordeev wrote: > On Wed, Oct 19, 2022 at 03:09:15PM -0700, John Stultz wrote: > > Hi John, > > [...] > > > So I'll go ahead and simplify the check to just the LONG_SOFTIRQ_MASK > > & (active | pending softirqs) check. This should avoid the need to > > pull the cpu_rq(cpu)->curr value and simplify things. > > In my reading of your approach if you find a way to additionally > indicate long softirqs being handled by the remote ksoftirqd, it > would cover all obvious/not-corner cases. How will that help? The long softirq executing inside ksoftirqd will disable preemption and prevent any RT task from executing. Did I miss something? thanks, - Joel