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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 74146E77188 for ; Fri, 3 Jan 2025 06:49:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=L8WSe4H2v/GqI7YH/KmjD+sC/5yZdirSTWKkaRsWuyM=; b=YYHivD31TfNdylfmfLj+d97unr mbTQaXPDOuacLxLS6quGJ5IiLDsMVuZlIIX9WMLvhxgB6xNDLmzM3CGCu1hTqK1FrE9HoxlF7bJT8 1NLJ8S0jxEcf3OIQd3vd5ha3J29vGJCezAHlELQf5S9xgPBvAK0BZ3ixxC712ls1G32dbzt3mAf4C dcT5bLyO6Yqp4FG3rNQUXEIL5GHRPwIASLCDWomXX9yYnOQOgkxl+1jEVheSCUfFTfH/p0w2L3LNa FD0goaYGF7MKnpRQFhZWjPcnAQASFAeVZC8aGs/YmlKTiB8R12oodKyB2ANROgKv3ESao+rmgWUFI igseZ6Gw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tTbVA-0000000CG0x-39JA; Fri, 03 Jan 2025 06:49:44 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tTbV5-0000000CFzQ-0mco for linux-nvme@lists.infradead.org; Fri, 03 Jan 2025 06:49:40 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 03BAE68BEB; Fri, 3 Jan 2025 07:49:26 +0100 (CET) Date: Fri, 3 Jan 2025 07:49:25 +0100 From: Christoph Hellwig To: Niklas Cassel Cc: Christoph Hellwig , Oliver Sang , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, virtualization@lists.linux.dev, linux-nvme@lists.infradead.org, Damien Le Moal , linux-btrfs@vger.kernel.org, linux-aio@kvack.org Subject: Re: [linus:master] [block] e70c301fae: stress-ng.aiol.ops_per_sec 49.6% regression Message-ID: <20250103064925.GB27984@lst.de> References: <202412122112.ca47bcec-lkp@intel.com> <20241213143224.GA16111@lst.de> <20241217045527.GA16091@lst.de> <20241217065614.GA19113@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250102_224939_358108_AE9C72C2 X-CRM114-Status: GOOD ( 21.71 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Jan 02, 2025 at 10:49:41AM +0100, Niklas Cassel wrote: > > > from below information, it seems an 'ahci' to me. but since I have limited > > > knowledge about storage driver, maybe I'm wrong. if you want more information, > > > please let us know. thanks a lot! > > > > Yes, this looks like ahci. Thanks a lot! > > Did this ever get resolved? > > I haven't seen a patch that seems to address this. > > AHCI (ata_scsi_queuecmd()) only issues a single command, so if there is any > reordering when issuing a batch of commands, my guess is that the problem > also affects SCSI / the problem is in upper layers above AHCI, i.e. SCSI lib > or block layer. I started looking into this before the holidays. blktrace shows perfectly sequential writes without any reordering using ahci, directly on the block device or using xfs and btrfs when using dd. I also started looking into what the test does and got as far as checking out the stress-ng source tree and looking at stress-aiol.c. AFAICS the default submission does simple reads and writes using increasing offsets. So if the test result isn't a fluke either the aio code does some weird reordering or btrfs does. Oliver, did the test also show any interesting results on non-btrfs setups?