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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE5DDC433F5 for ; Mon, 23 May 2022 11:01:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8C91D6B0007; Mon, 23 May 2022 07:01:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 878BF6B0008; Mon, 23 May 2022 07:01:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 773796B000A; Mon, 23 May 2022 07:01:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 66C0C6B0007 for ; Mon, 23 May 2022 07:01:06 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 36A116106E for ; Mon, 23 May 2022 11:01:06 +0000 (UTC) X-FDA: 79496715732.21.8E9D470 Received: from mail-wr1-f52.google.com (mail-wr1-f52.google.com [209.85.221.52]) by imf25.hostedemail.com (Postfix) with ESMTP id 5432CA000F for ; Mon, 23 May 2022 11:00:38 +0000 (UTC) Received: by mail-wr1-f52.google.com with SMTP id p10so2167229wrg.12 for ; Mon, 23 May 2022 04:01:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raspberrypi.com; s=google; h=message-id:date:mime-version:user-agent:subject:to:cc:references :from:in-reply-to:content-transfer-encoding; bh=7Gj0myDG7Upk1Lm/yIITVfKpkM1xaCwFPb15m2KrOlA=; b=SJc2DPtddEaRZtuiQIVwI9U6g2Kqmyg3NynK+fD7QTldXAL63VcMRo+aMpJExYDpea U61wuSKnmZudN9/aPDkW+8q2i6sI42HdU+daRbOBydwTH/40cNUSgVlse0Y2aAyMf2c5 M84vKj+sPSwuuOPh+WMeLIkLYg5u0mh0YUqnX4r/H0MM7ztqP4pL9mX9GZMSDnCcC/Eb JGCq9NAZ7xkWCQurfiXYTq3ZBPfihEm7fptSmT/Td81FKIlPYQCJRIcieZ7zpDRZQWaW wJJlN3j/UIGTboshXaa5yTkQil2BreC2vL3dzzRVBrCLzj0GOELRnczy6unvHZKSluZg mP2A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :to:cc:references:from:in-reply-to:content-transfer-encoding; bh=7Gj0myDG7Upk1Lm/yIITVfKpkM1xaCwFPb15m2KrOlA=; b=RYWmoK73osB4d8c8RVhmsX8FpVskKWLLJCiRIkFXb0mCmeYehoW1wZplKd18LkR63A Tn9W+IxLwn66Ttxk6ekx+QgKuEjeMeZSuyrdGAPAChvu5TLoHB78VDtJNEKeTsnW4Mt+ 3Urxh47WXS02ZSL5TYWvsZxssKekOUIjhz9q6eo6WbERvGdOMWxlaNgw0WT4ez8sr/9w 85f59gRIm1HD4kYJBPXilTn5u/GlWB+quI6x3gu6Z42LfNpLaw1vn6E/ynJLtHFVJOFb y3Q35Zw/nTQZr5uo/zPecLlO86oIx0xJ7KLWpo7C93YK3mrE6YcTJD7sMvsTBS1HnXKY ylNg== X-Gm-Message-State: AOAM531mdGAP8Avw5XDlJXoPhFP8/W7k9bp78PE64XbtuSfwMEYxw9vx aEs7XBDg6PKbmCOvLL1n1gp1ng== X-Google-Smtp-Source: ABdhPJx6MdtFMgPpDDHtWkV8+ZFaWG7x/MF24zzfaJQeetYugRp7nIBEH/k2SC8JHmNUjXnyYkNFsw== X-Received: by 2002:a5d:6406:0:b0:20e:5bf9:8e31 with SMTP id z6-20020a5d6406000000b0020e5bf98e31mr18094381wru.432.1653303663852; Mon, 23 May 2022 04:01:03 -0700 (PDT) Received: from ?IPV6:2a00:1098:3142:14:3110:d736:2a7:6aff? ([2a00:1098:3142:14:3110:d736:2a7:6aff]) by smtp.gmail.com with ESMTPSA id g10-20020adfa58a000000b0020e60baffd1sm6477332wrc.52.2022.05.23.04.01.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 23 May 2022 04:01:03 -0700 (PDT) Message-ID: Date: Mon, 23 May 2022 12:01:03 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: vchiq: Performance regression since 5.18-rc1 To: Stefan Wahren , paulmck@kernel.org Cc: Marcelo Tosatti , Andrew Morton , Nicolas Saenz Julienne , Borislav Petkov , Minchan Kim , Mel Gorman , Juri Lelli , Thomas Gleixner , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linux ARM , regressions@lists.linux.dev, riel@surriel.com, viro@zeniv.linux.org.uk References: <77d6d498-7dd9-03eb-60f2-d7e682bb1b20@i2se.com> <20220521234616.GO1790663@paulmck-ThinkPad-P17-Gen-1> <20220523044818.GS1790663@paulmck-ThinkPad-P17-Gen-1> <58cb7fbb-d317-83e6-0427-d3f3944b24b8@raspberrypi.com> From: Phil Elwell In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=raspberrypi.com header.s=google header.b=SJc2DPtd; spf=pass (imf25.hostedemail.com: domain of phil@raspberrypi.com designates 209.85.221.52 as permitted sender) smtp.mailfrom=phil@raspberrypi.com; dmarc=pass (policy=none) header.from=raspberrypi.com X-Rspam-User: X-Stat-Signature: cciyf5gsesy6m4zosbhxzc6d1hbu4z31 X-Rspamd-Queue-Id: 5432CA000F X-Rspamd-Server: rspam01 X-HE-Tag: 1653303638-166295 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Stefan, On 23/05/2022 11:48, Stefan Wahren wrote: > Hi Phil, > > Am 23.05.22 um 11:29 schrieb Phil Elwell: >> Hi Stefan, >> >> On 23/05/2022 07:19, Stefan Wahren wrote: >>> Hi Paul, >>> >>> Am 23.05.22 um 06:48 schrieb Paul E. McKenney: >>>> On Sun, May 22, 2022 at 05:11:36PM +0200, Stefan Wahren wrote: >>>>> Hi Paul, >>>>> >>>>> Am 22.05.22 um 01:46 schrieb Paul E. McKenney: >>>>>> On Sun, May 22, 2022 at 01:22:00AM +0200, Stefan Wahren wrote: >>>>>>> Hi, >>>>>>> >>>>>>> while testing the staging/vc04_services/interface/vchiq_arm driver with my >>>>>>> Raspberry Pi 3 B+ (multi_v7_defconfig) i noticed a huge performance >>>>>>> regression since [ff042f4a9b050895a42cae893cc01fa2ca81b95c] mm: >>>>>>> lru_cache_disable: replace work queue synchronization with synchronize_rcu >>>>>>> >>>>>>> Usually i run "vchiq_test -f 1" to see the driver is still working [1]. >>>>>>> >>>>>>> Before commit: >>>>>>> >>>>>>> real    0m1,500s >>>>>>> user    0m0,068s >>>>>>> sys    0m0,846s >>>>>>> >>>>>>> After commit: >>>>>>> >>>>>>> real    7m11,449s >>>>>>> user    0m2,049s >>>>>>> sys    0m0,023s >>>>>>> >>>>>>> Best regards >>>>>>> >>>>>>> [1] - https://github.com/raspberrypi/userland >>>>>> Please feel free to try the patch shown below.  Or the pair of patches >>>>>> from Rik here: >>>>>> >>>>>> https://lore.kernel.org/lkml/20220218183114.2867528-2-riel@surriel.com/ >>>>>> https://lore.kernel.org/lkml/20220218183114.2867528-3-riel@surriel.com/ >>>>> I tried your patch and Rik's patches but in both cases vchiq_test runs 7 >>>>> minutes instead of ~ 1 second. >>>> That is surprising.  Do you boot with rcupdate.rcu_normal=1? >>> No, not explicit. >>>>    That would >>>> nullify my patch, but I would expect that Rik's patch would still provide >>>> increased performance even in that case. >>> I will retest with a fresh SD card image. >>>> >>>> Could you please characterize where the slowdown is occurring? >>> >>> Unfortunately i don't have a deep insight into driver and vchiq_test tool. >>> Just a user view. >>> >>> Do you think an strace would be a good starting point? >>> >>> @Phil Any advices to analyse this issue? >> >> Sending many small control packets: >> >>    vchiq_test -c 1 10000 >> >> essentially tests interrupt latency. Using a small number of large bulk >> transfers: >> >>    vchiq_test -b 10000 1 >> >> becomes a test of how long it takes to lock down pages. It also tests DMA >> transfer speeds, but since the DMA is run by the firmware (which you aren't >> changing), I think you can rule that. > Thanks i will try. >> >> You may also find it helpful to include "force_turbo=1" in config.txt for more >> predictable results. >> >> By the way, running our 5.18-rc7-based branch on a 3B+ I'm not seeing any >> performance problems: > I assume you are using arm/bcm2709_defconfig and not arm/multi_v7_defconfig as me? That's correct. Simply switching to multi_v7_defconfig breaks vchiq completely, presumably because it doesn't define CONFIG_BCM2835_VCHIQ. Phil >> >> pi@raspberrypi:~$ time vchiq_test -f 1 >> Functional test - iters:1 >> ======== iteration 1 ======== >> Testing bulk transfer for alignment. >> Testing bulk transfer at PAGE_SIZE. >> >> real    0m0.512s >> user    0m0.042s >> sys     0m0.165s >> >> Phil