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=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E2DE3C433E6 for ; Thu, 4 Feb 2021 18:21:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A153464F44 for ; Thu, 4 Feb 2021 18:21:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239003AbhBDSUt (ORCPT ); Thu, 4 Feb 2021 13:20:49 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:31834 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238784AbhBDSUD (ORCPT ); Thu, 4 Feb 2021 13:20:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612462717; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=85mWqPkwgft3QumNJIv0lzUNsiwA9K0lxEl6eklMhqo=; b=TgaVa54lRxDKaLVTAjR9dUeqfZSC4Zpg8ljRdP0E7HZptnyDMWypdvfnWd1YVVpES4SAKN v3W7LTa3WPBN1sn6vZZnaAWH5KSXfu8RVkNX8XIHACL9xyEjFTBMgxVYko9xTX+vASSxwR uDD9FXx/roJmVNOckbKkLRAmqiDzcNM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-206-9cQB1pZEPteiZ6b-1P1WOw-1; Thu, 04 Feb 2021 13:18:35 -0500 X-MC-Unique: 9cQB1pZEPteiZ6b-1P1WOw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E564F80196E; Thu, 4 Feb 2021 18:18:32 +0000 (UTC) Received: from fuller.cnet (ovpn-112-6.gru2.redhat.com [10.97.112.6]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 46B4460C05; Thu, 4 Feb 2021 18:18:20 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 20E9D4178901; Thu, 4 Feb 2021 15:15:46 -0300 (-03) Date: Thu, 4 Feb 2021 15:15:46 -0300 From: Marcelo Tosatti To: Thomas Gleixner Cc: Nitesh Narayan Lal , Robin Murphy , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, frederic@kernel.org, juri.lelli@redhat.com, abelits@marvell.com, bhelgaas@google.com, linux-pci@vger.kernel.org, rostedt@goodmis.org, mingo@kernel.org, peterz@infradead.org, davem@davemloft.net, akpm@linux-foundation.org, sfr@canb.auug.org.au, stephen@networkplumber.org, rppt@linux.vnet.ibm.com, jinyuqi@huawei.com, zhangshaokun@hisilicon.com Subject: Re: [Patch v4 1/3] lib: Restrict cpumask_local_spread to houskeeping CPUs Message-ID: <20210204181546.GA30113@fuller.cnet> References: <20200625223443.2684-1-nitesh@redhat.com> <20200625223443.2684-2-nitesh@redhat.com> <3e9ce666-c9cd-391b-52b6-3471fe2be2e6@arm.com> <20210127121939.GA54725@fuller.cnet> <87r1m5can2.fsf@nanos.tec.linutronix.de> <20210128165903.GB38339@fuller.cnet> <87h7n0de5a.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87h7n0de5a.fsf@nanos.tec.linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, Jan 28, 2021 at 09:01:37PM +0100, Thomas Gleixner wrote: > On Thu, Jan 28 2021 at 13:59, Marcelo Tosatti wrote: > >> The whole pile wants to be reverted. It's simply broken in several ways. > > > > I was asking for your comments on interaction with CPU hotplug :-) > > Which I answered in an seperate mail :) > > > So housekeeping_cpumask has multiple meanings. In this case: > > ... > > > So as long as the meaning of the flags are respected, seems > > alright. > > Yes. Stuff like the managed interrupts preference for housekeeping CPUs > when a affinity mask spawns housekeeping and isolated is perfectly > fine. It's well thought out and has no limitations. > > > Nitesh, is there anything preventing this from being fixed > > in userspace ? (as Thomas suggested previously). > > Everything with is not managed can be steered by user space. Yes, but it seems to be racy (that is, there is a window where the interrupt can be delivered to an isolated CPU). ethtool -> xgbe_set_channels -> xgbe_full_restart_dev -> xgbe_alloc_memory -> xgbe_alloc_channels -> cpumask_local_spread Also ifconfig eth0 down / ifconfig eth0 up leads to cpumask_spread_local. How about adding a new flag for isolcpus instead?