From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-f41.google.com ([209.85.167.41]:43666 "EHLO mail-lf1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726691AbfJPRos (ORCPT ); Wed, 16 Oct 2019 13:44:48 -0400 Received: by mail-lf1-f41.google.com with SMTP id u3so18193263lfl.10 for ; Wed, 16 Oct 2019 10:44:46 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: smitha sunder Date: Wed, 16 Oct 2019 10:18:26 -0700 Message-ID: Subject: Re: unaligned IO and starting LBA Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: "Elliott, Robert (Servers)" Cc: fio Hi Robert, Since I want to use blocksize_unaligned=3D1 , I had to get rid of direct=3D= 1 : Per man page : blocksize_unaligned, bs_unaligned If set, any size in blocksize_range may be used. This typically won't work with direct I/O, as that normally requires sector alignment. # fio --name=3Djob1 --filename=3D/dev/nvme0n1 --rw=3Drandwrite --ioengine=3Dlibaio --number_ios=3D1 --debug=3Dio --bs_unaligned=3D1 --bs=3D1029 --direct=3D1 fio: set debug option io fio: bs_unaligned may not work with raw io Thanks smitha On Wed, Oct 16, 2019 at 8:12 AM Elliott, Robert (Servers) wrote: > > > > > -----Original Message----- > > From: fio-owner@vger.kernel.org [mailto:fio-owner@vger.kernel.org] On B= ehalf Of smitha sunder > > Sent: Tuesday, October 15, 2019 4:37 PM > > To: fio > > Subject: unaligned IO and starting LBA > > > > Hello, > > > > > > > > I have a 512 byte formatted nvme drive and I want to send an unaligned > > IO and here=E2=80=99s the fio command line I am using , fio version fio= -3.7 > > > > # fio --name=3Djob1 --filename=3D/dev/nvme0n1 --rw=3Drandwrite > > --ioengine=3Dlibaio --number_ios=3D1 --debug=3Dio --bs_unaligned=3D1 > > --bs=3D1029 > ... > > Shouldn=E2=80=99t I see D7BD7CE as the starting LBA for the write based= on the > > above offset (0x1af7af9cec) ? > > Without direct=3D1 you're exercising the OS page cache logic, > not directly accessing the drive. >