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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 8142BC433E0 for ; Wed, 13 Jan 2021 16:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DD5D23444 for ; Wed, 13 Jan 2021 16:46:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727818AbhAMQqG (ORCPT ); Wed, 13 Jan 2021 11:46:06 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:27981 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727768AbhAMQqF (ORCPT ); Wed, 13 Jan 2021 11:46:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610556279; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=B2nZaowcmYpAm6+Q7xTb3SoumDbJkYtkPecNpTcfdqc=; b=gvmR8F0EbASo0nL0dV8lZ1GlhFmyJlkBeGGMQffQY7SY/sauHd0Ofyh1Pge1YL3vchdVmY fs6YYNA9X5Rxl3krfkKAd9u5R/ITRkqRaExL3QpNQfSTeVXHixtErfW2ZP739RYzZyvBiI 4VPiU4tJmeBHnXHlINjuGaRhXOOdzYM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-208-n2t6kthuPH2jhsKcw9bewQ-1; Wed, 13 Jan 2021 11:44:35 -0500 X-MC-Unique: n2t6kthuPH2jhsKcw9bewQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0654A806660; Wed, 13 Jan 2021 16:44:33 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C7E0C6062F; Wed, 13 Jan 2021 16:44:32 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id 10DGiWGW005756; Wed, 13 Jan 2021 11:44:32 -0500 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id 10DGiUmf005752; Wed, 13 Jan 2021 11:44:31 -0500 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Wed, 13 Jan 2021 11:44:30 -0500 (EST) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Zhongwei Cai cc: Mingkai Dong , Matthew Wilcox , Andrew Morton , Jan Kara , Steven Whitehouse , Eric Sandeen , Dave Chinner , "Theodore Ts'o" , Wang Jianchao , "Tadakamadla, Rajesh" , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org Subject: Re: Expense of read_iter In-Reply-To: <2041983017.5681521.1610459100858.JavaMail.zimbra@sjtu.edu.cn> Message-ID: References: <20210107151125.GB5270@casper.infradead.org> <17045315-CC1F-4165-B8E3-BA55DD16D46B@gmail.com> <2041983017.5681521.1610459100858.JavaMail.zimbra@sjtu.edu.cn> User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 12 Jan 2021, Zhongwei Cai wrote: > > I'm working with Mingkai on optimizations for Ext4-dax. What specific patch are you working on? Please, post it somewhere. > We think that optmizing the read-iter method cannot achieve the > same performance as the read method for Ext4-dax. > We tried Mikulas's benchmark on Ext4-dax. The overall time and perf > results are listed below: > > Overall time of 2^26 4KB read. > > Method Time > read 26.782s > read-iter 36.477s What happens if you use this trick ( https://lkml.org/lkml/2021/1/11/1612 ) - detect in the "read_iter" method that there is just one segment and treat it like a "read" method. I think that it should improve performance for your case. Mikulas