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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,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 3D51FC11F6A for ; Fri, 2 Jul 2021 10:05:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 235F1613FA for ; Fri, 2 Jul 2021 10:05:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231437AbhGBKHs (ORCPT ); Fri, 2 Jul 2021 06:07:48 -0400 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:56083 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231302AbhGBKHr (ORCPT ); Fri, 2 Jul 2021 06:07:47 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R161e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=yaohuiwang@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0UeT3pAQ_1625220302; Received: from Dillions-MBP-16.local(mailfrom:yaohuiwang@linux.alibaba.com fp:SMTPD_---0UeT3pAQ_1625220302) by smtp.aliyun-inc.com(127.0.0.1); Fri, 02 Jul 2021 18:05:03 +0800 Subject: Re: [PATCH v3 1/2] x86/ioremap: fix the pfn calculation mistake in __ioremap_check_ram() To: Dave Hansen , tglx@linutronix.de Cc: luto@kernel.org, peterz@infradead.org, mingo@redhat.com, bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org, luoben@linux.alibaba.com, Tom Lendacky , Brijesh Singh References: <20210621123419.2976-1-yaohuiwang@linux.alibaba.com> <20210621123419.2976-2-yaohuiwang@linux.alibaba.com> <94a38542-b639-37e4-1b53-29b59c5ea655@intel.com> From: Yaohui Wang Message-ID: <34bae667-180f-ce97-ee55-12e13ff28ca0@linux.alibaba.com> Date: Fri, 2 Jul 2021 18:05:02 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <94a38542-b639-37e4-1b53-29b59c5ea655@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/7/1 22:41, Dave Hansen wrote: > Was this issue found by inspection, or is it causing an actual problem > in practice? This issus truly caused terrible perforamnce downgrade in the practice. When developing an out of tree module in our testing environment, invoking ioremap() on normal RAM causes apparent CLI lag. The Unixbench score also decreases a lot (5x slowdown in the worst case). Debugging such performance issue is extremely difficult, especially when the code of the faulty module itself is already very complex. I tested the system in many aspects before finally located this problem. > Also, it would be really nice to include the original authors when you > send Fixes: for patches. BTW, scripts/get_maintainer.pl would have done > this for you. I've added Tom and Brijesh. Please cc them in the future. I'll pay attention to this in the future. Thank you for your time and patience!