From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 From: Spelic Date: Mon, 3 Jan 2011 04:26:57 -0700 Subject: Re: Again on IOPS higher than expected in randwrite 4k Message-ID: <4D21B281.8040501@shiftmail.org> References: <4D1FFB1B.1010000@shiftmail.org> <4D21AD7D.7090707@fusionio.com> In-Reply-To: <4D21AD7D.7090707@fusionio.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Jens Axboe Cc: "fio@vger.kernel.org" List-ID: On 01/03/2011 12:05 PM, Jens Axboe wrote: > On 2011-01-02 05:12, Spelic wrote: > =20 >> Hello, I just subscribed, I noticed that some 20 days ago there was a >> thread on "IOPS higher than expected on randwrite, direct=3D1 tests" on >> this ML. It's curious because I subscribed to report basically the >> same thing. >> >> With Hitachi 7k1000 HDS721010KLA330 (maybe the same drives as >> Sebastian) I am seeing the same problem of IOPS too high with FIO, up >> to 300 IOPS per disk (up to 500 per disk with storsave=3Dperformance on >> my 3ware but that's probably cheating). I am doing 4k random writes. >> >> I followed the discussion, I don't really agree with the point at the >> end of the discussion, so I'd like to bump this thread again. >> >> My impression is that these drives do not honor the flush or FUA. >> (Directio uses flush or FUA right? you can be sure that data is on the >> platters after directio right? Anyway I also set fsync=3D1 and nothing >> changed) >> =20 > O_DIRECT does not imply flush of FUA, I'm afraid. It arguably should use > FUA, but currently it does not. > =20 Oh I see. But if I add fsync=3D1 I still get 300 IOPS per disk, or even 500 on very=20 short seeks, so again I'd say these disks are cheating. Do you agree?