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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 EEEAAC47E48 for ; Tue, 6 Jul 2021 05:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D03A761977 for ; Tue, 6 Jul 2021 05:25:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230077AbhGFF2G (ORCPT ); Tue, 6 Jul 2021 01:28:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230008AbhGFF2F (ORCPT ); Tue, 6 Jul 2021 01:28:05 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69CC2C061574; Mon, 5 Jul 2021 22:25:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=V9RQWVqTQeoAkXWE4Ne/8f/6vQUcvWf8z6pk/6TsLT0=; b=g787ZCRwxrrOMFbum+GrK7ZTBw HhsrDl6Ucf1UNaYQJZTcDWa7fcb+NxrQv1VXAVkCNyKeeYJro3+P5MZcSb/dogGbNtfH3EXf9HFD1 esxHkyJccGdewMrAdZVvGQ0OvDLPQYnQTLmsecxcqZtEahFR+Mo6FT765bhN0sPwq+msyDz6DkfMK YKozDJoKMrhkkrmoRPqaSfMl1YJsz8R3WDVt2j5qSt4+y18lbr2LZ1fJ/XUnb9jxjwHThWcZ0DJZ/ MBwY10Bth1TMSk53G/n468zN1q5st7NXtgf3xexqzFcxpxoaC7DlDovv4hqi1ZHO7/BqaHZTn1h54 YnlQWIJw==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0dZz-00Ardc-Db; Tue, 06 Jul 2021 05:25:11 +0000 Date: Tue, 6 Jul 2021 06:25:07 +0100 From: Christoph Hellwig To: brookxu Cc: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] block: fix the problem of io_ticks becoming smaller Message-ID: References: <1625521646-1069-1-git-send-email-brookxu.cn@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1625521646-1069-1-git-send-email-brookxu.cn@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 06, 2021 at 05:47:26AM +0800, brookxu wrote: > From: Chunguang Xu > > On the IO submission path, blk_account_io_start() may interrupt > the system interruption. When the interruption returns, the value > of part->stamp may have been updated by other cores, so the time > value collected before the interruption may be less than part-> > stamp. So when this happens, we should do nothing to make io_ticks > more accurate? For kernels less than 5.0, this may cause io_ticks > to become smaller, which in turn may cause abnormal ioutil values. > > v3: update the commit log > v2: sorry, fix compile error due to the missed ')' > > Signed-off-by: Chunguang Xu The change looks good: Reviewed-by: Christoph Hellwig Although I still have trouble understanding the commit log, especially the last sentence.