From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EFC3C18E3F; Fri, 3 Jan 2025 06:49:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735886972; cv=none; b=I6xooidL7YDiwFZp/b8A0sSEfT+tl+lFuqEiJBkgbXxCjMSlK0ABggD6jkPUSAp8Fu+C9418xpRQ6lXsRxT5jXMZ2zBpkyEjpKy5gSASkJyrFonGtI+P/S8fR3ZmwKvmxoBECYcNDw/UXYJ82uRuDOZjIisQU4X8xpuNTzrZqTc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735886972; c=relaxed/simple; bh=hlWHq0OMSTWoCnf+7Roi9teoijwZHWsV5MnA9LcUc0Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LZMHvlyWyp0iroB1cLwWWtro4WQj1huL6HrHgis2p4vQPRjoEk9Z5cXZjZJpn8PvlfsKJuWCqmxFK5KduVru2CDXlElbKej3WIMx1asg8Ld+8Tq35cSH25nHt94rV9xzmrin0kg+IFB7XihM4SlJ/h8HQhk1CcsJVwgymJn6MRQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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) 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?