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=-7.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 B0A24C56201 for ; Mon, 26 Oct 2020 23:08:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 783FE2087C for ; Mon, 26 Oct 2020 23:08:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395438AbgJZXIN (ORCPT ); Mon, 26 Oct 2020 19:08:13 -0400 Received: from mga11.intel.com ([192.55.52.93]:39672 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394676AbgJZXIN (ORCPT ); Mon, 26 Oct 2020 19:08:13 -0400 IronPort-SDR: C0HKN+3xVxuhHup+b8wKNn5CD+V6moJckNtJIXbUN05IuMXEg5AFWXEUu8Z85WuxQatCL/28zj bU9dRqa88mTA== X-IronPort-AV: E=McAfee;i="6000,8403,9786"; a="164500454" X-IronPort-AV: E=Sophos;i="5.77,421,1596524400"; d="scan'208";a="164500454" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2020 16:08:12 -0700 IronPort-SDR: zy8W979PBVagL8i+Jv+r805cLR1FVBAasdYfpwLnnY5dMEYS9mo977q0BeEUHtu8ZSPkUShL6e ejjJSj2+O2cA== X-IronPort-AV: E=Sophos;i="5.77,421,1596524400"; d="scan'208";a="524468975" Received: from jekeller-mobl1.amr.corp.intel.com (HELO [10.212.215.218]) ([10.212.215.218]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Oct 2020 16:08:10 -0700 Subject: Re: [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to housekeeping CPUs To: Thomas Gleixner , Nitesh Narayan Lal , Marcelo Tosatti Cc: Peter Zijlstra , helgaas@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-pci@vger.kernel.org, intel-wired-lan@lists.osuosl.org, frederic@kernel.org, sassmann@redhat.com, jesse.brandeburg@intel.com, lihong.yang@intel.com, jeffrey.t.kirsher@intel.com, jlelli@redhat.com, hch@infradead.org, bhelgaas@google.com, mike.marciniszyn@intel.com, dennis.dalessandro@intel.com, thomas.lendacky@amd.com, jiri@nvidia.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, lgoncalv@redhat.com, Jakub Kicinski References: <20201019111137.GL2628@hirez.programming.kicks-ass.net> <20201019140005.GB17287@fuller.cnet> <20201020073055.GY2611@hirez.programming.kicks-ass.net> <078e659e-d151-5bc2-a7dd-fe0070267cb3@redhat.com> <20201020134128.GT2628@hirez.programming.kicks-ass.net> <6736e643-d4ae-9919-9ae1-a73d5f31463e@redhat.com> <260f4191-5b9f-6dc1-9f11-085533ac4f55@redhat.com> <20201023085826.GP2611@hirez.programming.kicks-ass.net> <9ee77056-ef02-8696-5b96-46007e35ab00@redhat.com> <87ft6464jf.fsf@nanos.tec.linutronix.de> <20201026173012.GA377978@fuller.cnet> <875z6w4xt4.fsf@nanos.tec.linutronix.de> <86f8f667-bda6-59c4-91b7-6ba2ef55e3db@intel.com> <87v9ew3fzd.fsf@nanos.tec.linutronix.de> <85b5f53e-5be2-beea-269a-f70029bea298@intel.com> <87lffs3bd6.fsf@nanos.tec.linutronix.de> <959997ee-f393-bab0-45c0-4144c37b9185@redhat.com> <875z6w38n4.fsf@nanos.tec.linutronix.de> From: Jacob Keller Organization: Intel Corporation Message-ID: <586e249a-1078-9fe9-22d4-b3c1ec0a3a5e@intel.com> Date: Mon, 26 Oct 2020 16:08:08 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.3.3 MIME-Version: 1.0 In-Reply-To: <875z6w38n4.fsf@nanos.tec.linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 10/26/2020 3:49 PM, Thomas Gleixner wrote: > On Mon, Oct 26 2020 at 18:22, Nitesh Narayan Lal wrote: >> On 10/26/20 5:50 PM, Thomas Gleixner wrote: >>> But I still think that for curing that isolation stuff we want at least >>> some information from the driver. Alternative solution would be to grant >>> the allocation of interrupts and queues and have some sysfs knob to shut >>> down queues at runtime. If that shutdown results in releasing the queue >>> interrupt (via free_irq()) then the vector exhaustion problem goes away. >> >> I think this is close to what I and Marcelo were discussing earlier today >> privately. >> >> I don't think there is currently a way to control the enablement/disablement of >> interrupts from the userspace. > > You cannot just disable the interrupt. You need to make sure that the > associated queue is shutdown or quiesced _before_ the interrupt is shut > down. > > Thanks, > > tglx > Could this be handled with a callback to the driver/hw? I know Intel HW should support this type of quiesce/shutdown. Thanks, Jake