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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 DE3CAC2D0E2 for ; Tue, 22 Sep 2020 20:58:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FFCD2371F for ; Tue, 22 Sep 2020 20:58:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600808290; bh=TAvOwxdUSSf8dMLys+bd/PzI7Tqp/e7DVoXkrTOUAiI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=p8wNLEpCD8cyVGbdvEgP+QoQl+BoHdIU4GetjFvFV7EzAOnhhc08cPwTENZg5pPLY JuQUXSBIj4jvtf94uCXCKYaPKjNlMTpHBVrM3012f8FaG+Hh+Yjvt4OYPOoZWQ5TqC H+mMO/mRdpAKf6i/ZGb00iTFlf013iaM54Fvg+s8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726661AbgIVU6K (ORCPT ); Tue, 22 Sep 2020 16:58:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:38428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726448AbgIVU6J (ORCPT ); Tue, 22 Sep 2020 16:58:09 -0400 Received: from localhost (lfbn-ncy-1-588-162.w81-51.abo.wanadoo.fr [81.51.203.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6503623600; Tue, 22 Sep 2020 20:58:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600808288; bh=TAvOwxdUSSf8dMLys+bd/PzI7Tqp/e7DVoXkrTOUAiI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qj13ocgnkXJAez0TGZR3gQzFaRpUp8hb6SZtLcZ+PxAr+4PzcI5QwU8Jjf5wbgjzl 7Tr7hS5Muy52iGsanhGHHpU6A2UWkmI7QeZwOU0nH6M7qHcoOC539vS+i2dZF2eHxi q4bZ5SoYnZ3KPN/P13yJbNL5RRWMHMysML8FKMYc= Date: Tue, 22 Sep 2020 22:58:06 +0200 From: Frederic Weisbecker To: Nitesh Narayan Lal Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, mtosatti@redhat.com, sassmann@redhat.com, jeffrey.t.kirsher@intel.com, jacob.e.keller@intel.com, jlelli@redhat.com, hch@infradead.org, bhelgaas@google.com, mike.marciniszyn@intel.com, dennis.dalessandro@intel.com, thomas.lendacky@amd.com, jerinj@marvell.com, mathias.nyman@intel.com, jiri@nvidia.com Subject: Re: [RFC][Patch v1 1/3] sched/isolation: API to get num of hosekeeping CPUs Message-ID: <20200922205805.GD5217@lenoir> References: <20200909150818.313699-1-nitesh@redhat.com> <20200909150818.313699-2-nitesh@redhat.com> <20200921234044.GA31047@lenoir> <20200922100817.GB5217@lenoir> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Sep 22, 2020 at 09:50:55AM -0400, Nitesh Narayan Lal wrote: > On 9/22/20 6:08 AM, Frederic Weisbecker wrote: > TBH I don't have a very strong case here at the moment. > But still, IMHO, this will force the user to have both managed irqs and > nohz_full in their environments to avoid these kinds of issues. Is that how > we would like to proceed? Yep that sounds good to me. I never know how much we want to split each and any of the isolation features but I'd rather stay cautious to separate HK_FLAG_TICK from the rest, just in case running in nohz_full mode ever becomes interesting alone for performance and not just latency/isolation. But look what you can do as well: diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 5a6ea03f9882..9df9598a9e39 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -141,7 +141,7 @@ static int __init housekeeping_nohz_full_setup(char *str) unsigned int flags; flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | - HK_FLAG_MISC | HK_FLAG_KTHREAD; + HK_FLAG_MISC | HK_FLAG_KTHREAD | HK_FLAG_MANAGED_IRQ; return housekeeping_setup(str, flags); } "nohz_full=" has historically gathered most wanted isolation features. It can as well isolate managed irqs. > > And then can we rename it to housekeeping_num_online()? > > It could be just me, but does something like hk_num_online_cpus() makes more > sense here? Sure, that works as well. Thanks.