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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75D23CCA47A for ; Tue, 14 Jun 2022 14:14:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242250AbiFNOOj (ORCPT ); Tue, 14 Jun 2022 10:14:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233498AbiFNOOi (ORCPT ); Tue, 14 Jun 2022 10:14:38 -0400 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D18CF28704; Tue, 14 Jun 2022 07:14:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1655216076; x=1686752076; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=0uq+vPn9P86+eSA1af5GDSL4gdgJ3UTG153tOxE/IIg=; b=yh7alZGDRwLh+1n+KB2uLlOYjtsfBSD3tE5t5FxhC6NDkr0R65h2LT2S ImKBBlpwYpBi4jXCZhx09sLVzujwYOWpGcZPPn6J3UN22kha7HPmbqK/O kRdZhcetb5sqZIQLQgHGwTA5O9ZfIJqA7XeCqlmeTaaefiO1tfJDY/8TC k=; Received: from unknown (HELO ironmsg01-sd.qualcomm.com) ([10.53.140.141]) by alexa-out-sd-01.qualcomm.com with ESMTP; 14 Jun 2022 07:14:36 -0700 X-QCInternal: smtphost Received: from nasanex01b.na.qualcomm.com ([10.46.141.250]) by ironmsg01-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jun 2022 07:14:34 -0700 Received: from [10.50.56.0] (10.80.80.8) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 14 Jun 2022 07:14:30 -0700 Message-ID: <88780123-32a3-ab34-cd3d-01e4a3421f03@quicinc.com> Date: Tue, 14 Jun 2022 19:44:27 +0530 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: Commit 282d8998e997 (srcu: Prevent expedited GPs and blocking readers from consuming CPU) cause qemu boot slow Content-Language: en-US To: "zhangfei.gao@foxmail.com" , Shameerali Kolothum Thodi , "paulmck@kernel.org" CC: Paolo Bonzini , Zhangfei Gao , "linux-kernel@vger.kernel.org" , "rcu@vger.kernel.org" , Lai Jiangshan , Josh Triplett , Mathieu Desnoyers , Matthew Wilcox , "mtosatti@redhat.com" , Auger Eric , "chenxiang (M)" References: <20220612162029.GR1790663@paulmck-ThinkPad-P17-Gen-1> <20220612164002.GA1242564@paulmck-ThinkPad-P17-Gen-1> <560f7d27-fe38-0db9-834a-50dda5fa6157@redhat.com> <20220612184944.GU1790663@paulmck-ThinkPad-P17-Gen-1> <20220613035711.GY1790663@paulmck-ThinkPad-P17-Gen-1> <20220613041652.GA3976000@paulmck-ThinkPad-P17-Gen-1> <20220613121831.GA1790663@paulmck-ThinkPad-P17-Gen-1> <20220613145900.GC1790663@paulmck-ThinkPad-P17-Gen-1> <7b6c983b21d44119b61716a66de397ed@huawei.com> From: Neeraj Upadhyay In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01b.na.qualcomm.com (10.46.141.250) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/14/2022 7:33 PM, zhangfei.gao@foxmail.com wrote: > > > On 2022/6/14 下午8:19, Neeraj Upadhyay wrote: >> >>> >>> 5.18-rc4 based               ~8sec >>> >>> 5.19-rc1                     ~2m43sec >>> >>> 5.19-rc1+fix1                 ~19sec >>> >>> 5.19-rc1-fix2                 ~19sec >>> >> >> If you try below diff on top of either 5.19-rc1+fix1 or 5.19-rc1-fix2 >> ; does it show any difference in boot time? >> >> --- a/kernel/rcu/srcutree.c >> +++ b/kernel/rcu/srcutree.c >> @@ -706,7 +706,7 @@ static void srcu_schedule_cbs_snp(struct >> srcu_struct *ssp, struct srcu_node *snp >>   */ >>  static void srcu_gp_end(struct srcu_struct *ssp) >>  { >> -       unsigned long cbdelay; >> +       unsigned long cbdelay = 1; >>         bool cbs; >>         bool last_lvl; >>         int cpu; >> @@ -726,7 +726,9 @@ static void srcu_gp_end(struct srcu_struct *ssp) >>         spin_lock_irq_rcu_node(ssp); >>         idx = rcu_seq_state(ssp->srcu_gp_seq); >>         WARN_ON_ONCE(idx != SRCU_STATE_SCAN2); >> -       cbdelay = !!srcu_get_delay(ssp); >> +       if (ULONG_CMP_LT(READ_ONCE(ssp->srcu_gp_seq), >> READ_ONCE(ssp->srcu_gp_seq_needed_exp))) >> +               cbdelay = 0; >> + >>         WRITE_ONCE(ssp->srcu_last_gp_end, ktime_get_mono_fast_ns()); >> > Test here: > qemu: https://github.com/qemu/qemu/tree/stable-6.1 > kernel: > https://github.com/Linaro/linux-kernel-uadk/tree/uacce-devel-5.19-srcu-test > (in case test patch not clear, push in git tree) > > Hardware: aarch64 > > 1. 5.18-rc6 > real    0m8.402s > user    0m3.015s > sys     0m1.102s > > 2. 5.19-rc1 > real    2m41.433s > user    0m3.097s > sys     0m1.177s > > 3. 5.19-rc1 + fix1 from Paul > real    2m43.404s > user    0m2.880s > sys     0m1.214s > > 4. 5.19-rc1 + fix2: fix1 + Remove "if (!jbase)" block > real    0m15.262s > user    0m3.003s > sys     0m1.033s > > When build kernel in the meantime, load time become longer. > > 5. 5.19-rc1 + fix3: fix1 + SRCU_MAX_NODELAY_PHASE 1000000 > real    0m15.215s > user    0m2.942s > sys    0m1.172s > > 6. 5.19-rc1 + fix4: fix1 + Neeraj's change of srcu_gp_end　 > real    1m23.936s > user    0m2.969s > sys    0m1.181s > Thanks for this data. Can you please share below test combo also? 7. 5.19-rc1 + fix5: fix2 + Neeraj's change of srcu_gp_end 8. 5.19-rc1 + fix6: fix3 + Neeraj's change of srcu_gp_end Thanks Neeraj > More test details: https://docs.qq.com/doc/DRXdKalFPTVlUbFN5 > > Thanks >