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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 96F1DC282DA for ; Thu, 31 Jan 2019 23:52:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 735B32087F for ; Thu, 31 Jan 2019 23:52:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728457AbfAaXwR (ORCPT ); Thu, 31 Jan 2019 18:52:17 -0500 Received: from ale.deltatee.com ([207.54.116.67]:52340 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726132AbfAaXwQ (ORCPT ); Thu, 31 Jan 2019 18:52:16 -0500 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1gpM7v-0005lf-5k; Thu, 31 Jan 2019 16:52:12 -0700 To: Dave Jiang , linux-kernel@vger.kernel.org, linux-ntb@googlegroups.com, linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kselftest@vger.kernel.org, Jon Mason , Bjorn Helgaas , Joerg Roedel Cc: Allen Hubbe , Serge Semin , Eric Pilmore References: <20190131185656.17972-1-logang@deltatee.com> <345197a6-89e6-c0de-5f7b-a646b5f396c9@intel.com> <29f7e3fe-5354-6156-1243-7248ffb2249f@deltatee.com> <7e3eed52-8e3a-c472-392a-5dc5689290ae@intel.com> <5f8b1616-a005-7658-978f-16466fcc3886@deltatee.com> From: Logan Gunthorpe Message-ID: <59a4f188-0d37-bf40-baf6-80b4fa46df52@deltatee.com> Date: Thu, 31 Jan 2019 16:52:10 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: epilmore@gigaio.com, fancer.lancer@gmail.com, allenbh@gmail.com, joro@8bytes.org, bhelgaas@google.com, jdmason@kudzu.us, linux-kselftest@vger.kernel.org, iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, linux-ntb@googlegroups.com, linux-kernel@vger.kernel.org, dave.jiang@intel.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH 0/9] Support using MSI interrupts in ntb_transport X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-01-31 4:48 p.m., Dave Jiang wrote: > > On 1/31/2019 4:41 PM, Logan Gunthorpe wrote: >> >> On 2019-01-31 3:46 p.m., Dave Jiang wrote: >>> I believe irqbalance writes to the file /proc/irq/N/smp_affinity. So >>> maybe take a look at the code that starts from there and see if it would >>> have any impact on your stuff. >> Ok, well on my system I can write to the smp_affinity all day and the >> MSI interrupts still work fine. > > Maybe your code is ok then. If the stats show up in /proc/interrupts > then you can see it moving to different cores. Yes, I did check that the stats change CPU in proc interrupts. > Yeah I'm not sure what to do about it either as I'm not super familiar > with that area either. Just making note of what I encountered. And you > are right, the updated info has to go over NTB for the other side to > write to the updated place. So there's a lot of latency involved. Ok, well I'll implement the callback anyway for v2. Better safe than sorry. We can operate on the assumption that someone thought of the race condition and if we ever see reports of lost interrupts we'll know where to look. Logan