From: Spelic <spelic@shiftmail.org>
To: Jens Axboe <JAxboe@fusionio.com>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: Again on IOPS higher than expected in randwrite 4k
Date: Mon, 3 Jan 2011 04:26:57 -0700 [thread overview]
Message-ID: <4D21B281.8040501@shiftmail.org> (raw)
In-Reply-To: <4D21AD7D.7090707@fusionio.com>
On 01/03/2011 12:05 PM, Jens Axboe wrote:
> On 2011-01-02 05:12, Spelic wrote:
>
>> Hello, I just subscribed, I noticed that some 20 days ago there was a
>> thread on "IOPS higher than expected on randwrite, direct=1 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=performance 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=1 and nothing
>> changed)
>>
> O_DIRECT does not imply flush of FUA, I'm afraid. It arguably should use
> FUA, but currently it does not.
>
Oh I see.
But if I add fsync=1 I still get 300 IOPS per disk, or even 500 on very
short seeks, so again I'd say these disks are cheating.
Do you agree?
next prev parent reply other threads:[~2011-01-03 11:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-02 4:12 Again on IOPS higher than expected in randwrite 4k Spelic
2011-01-03 11:05 ` Jens Axboe
2011-01-03 11:26 ` Spelic [this message]
2011-01-03 14:10 ` Jens Axboe
2011-01-05 11:45 ` Spelic
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