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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 9EC8FC2D0C0 for ; Mon, 23 Dec 2019 09:07:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7300C206CB for ; Mon, 23 Dec 2019 09:07:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577092069; bh=5z7sWIpaYqMbvpg6MeavV3NbeplPVUOZHTBPGO86TS4=; h=To:Subject:Date:From:Cc:In-Reply-To:References:List-ID:From; b=glm7niBvS+QWfxtfDMsg2POMZZTt4mFKK+FShOn1Yg1EDje41gQad3xrioHD2oxRh 7WsS/uj4mwWxGID6VBnsk6wnvJqL3Qk6V74JuVleCsp+I7eDF5mTHTgBhVYYo41amt gqpAWVA5iGj0dMYmb6lZGrKRfTEgE25KNp805uJA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726729AbfLWJHs (ORCPT ); Mon, 23 Dec 2019 04:07:48 -0500 Received: from inca-roads.misterjones.org ([213.251.177.50]:36622 "EHLO inca-roads.misterjones.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725974AbfLWJHs (ORCPT ); Mon, 23 Dec 2019 04:07:48 -0500 Received: from www-data by cheepnis.misterjones.org with local (Exim 4.80) (envelope-from ) id 1ijJgh-0007yn-Sh; Mon, 23 Dec 2019 10:07:39 +0100 To: Ming Lei Subject: Re: [PATCH RFC 1/1] genirq: Make threaded handler use irq affinity for managed interrupt X-PHP-Originating-Script: 0:main.inc MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 23 Dec 2019 09:07:39 +0000 From: Marc Zyngier Cc: John Garry , , "chenxiang (M)" , , , , , , , , In-Reply-To: <20191220233138.GB12403@ming.t460p> References: <20191214135641.5a817512@why> <7db89b97-1b9e-8dd1-684a-3eef1b1af244@huawei.com> <50d9ba606e1e3ee1665a0328ffac67ac@www.loen.fr> <68058fd28c939b8e065524715494de95@www.loen.fr> <687cbcc4-89d9-63ea-a246-ce2abaae501a@huawei.com> <0fd543f8ffd90f90deb691aea1c275b4@www.loen.fr> <20191220233138.GB12403@ming.t460p> Message-ID: X-Sender: maz@kernel.org User-Agent: Roundcube Webmail/0.7.2 X-SA-Exim-Connect-IP: X-SA-Exim-Rcpt-To: ming.lei@redhat.com, john.garry@huawei.com, tglx@linutronix.de, chenxiang66@hisilicon.com, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, hare@suse.com, hch@lst.de, axboe@kernel.dk, bvanassche@acm.org, peterz@infradead.org, mingo@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on cheepnis.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-12-20 23:31, Ming Lei wrote: > On Fri, Dec 20, 2019 at 03:38:24PM +0000, John Garry wrote: >> > > We've got some more results and it looks promising. >> > > >> > > So with your patch we get a performance boost of 3180.1K -> >> 3294.9K >> > > IOPS in the D06 SAS env. Then when we change the driver to use >> > > threaded interrupt handler (mainline currently uses tasklet), we >> get a >> > > boost again up to 3415K IOPS. >> > > >> > > Now this is essentially the same figure we had with using >> threaded >> > > handler + the gen irq change in spreading the handler CPU >> affinity. We >> > > did also test your patch + gen irq change and got a performance >> drop, >> > > to 3347K IOPS. >> > > >> > > So tentatively I'd say your patch may be all we need. >> > >> > OK. >> > >> > > FYI, here is how the effective affinity is looking for both SAS >> > > controllers with your patch: >> > > >> > > 74:02.0 >> > > irq 81, cpu list 24-29, effective list 24 cq >> > > irq 82, cpu list 30-35, effective list 30 cq >> > >> > Cool. >> > >> > [...] >> > >> > > As for your patch itself, I'm still concerned of possible >> regressions >> > > if we don't apply this effective interrupt affinity spread >> policy to >> > > only managed interrupts. >> > >> > I'll try and revise that as I post the patch, probably at some >> point >> > between now and Christmas. I still think we should find a way to >> > address this for the D05 SAS driver though, maybe by managing the >> > affinity yourself in the driver. But this requires >> experimentation. >> >> I've already done something experimental for the driver to manage >> the >> affinity, and performance is generally much better: >> >> >> https://github.com/hisilicon/kernel-dev/commit/e15bd404ed1086fed44da34ed3bd37a8433688a7 >> >> But I still think it's wise to only consider managed interrupts for >> now. >> >> > >> > > JFYI, about NVMe CPU lockup issue, there are 2 works on going >> here: >> > > >> > > >> https://lore.kernel.org/linux-nvme/20191209175622.1964-1-kbusch@kernel.org/T/#t >> > > >> > > >> > > >> https://lore.kernel.org/linux-block/20191218071942.22336-1-ming.lei@redhat.com/T/#t >> > > >> > >> > I've also managed to trigger some of them now that I have access >> to >> > a decent box with nvme storage. >> >> I only have 2x NVMe SSDs when this occurs - I should not be hitting >> this... >> >> Out of curiosity, have you tried >> > with the SMMU disabled? I'm wondering whether we hit some livelock >> > condition on unmapping buffers... >> >> No, but I can give it a try. Doing that should lower the CPU usage, >> though, >> so maybe masks the issue - probably not. > > Lots of CPU lockup can is performance issue if there isn't obvious > bug. > > I am wondering if you may explain it a bit why enabling SMMU may save > CPU a it? The other way around. mapping/unmapping IOVAs doesn't comes for free. I'm trying to find out whether the NVMe map/unmap patterns trigger something unexpected in the SMMU driver, but that's a very long shot. M. -- Jazz is not dead. It just smells funny...