From: Jens Axboe <axboe@kernel.dk>
To: Brian Fallik <bfallik@bamboom.com>
Cc: Jeff Moyer <jmoyer@redhat.com>,
"fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: fio file test patterns
Date: Wed, 31 Aug 2011 15:38:24 -0600 [thread overview]
Message-ID: <4E5EA9D0.10109@kernel.dk> (raw)
In-Reply-To: <4E5EA5DF.5040609@fusionio.com>
On 2011-08-31 15:21, Jens Axboe wrote:
>> I also have another (maybe related?) question. Apologies if this
>> belongs in a separate thread, but are there any notes explaining why
>> fio lays out the files before starting sequential writes? The
>> workload I was hoping to simulate is sustained, sequential writes to
>> disk. I'm trying to answer the question "How many simultaneous
>> 200kBps writers can we support?" Using my current jobs file, fio
>> starts by creating the files (e.g "foo0: Laying out IO file(s) (1
>> file(s) / 4MB)") before it starts processing. However, creating the
>> files in advance accounts for a chunk of performance that doesn't seem
>> to be measured by fio. Am I misunderstanding how to configure fio or
>> its intended usage?
>
> You should be able to set overwrite=0 to avoid that. Are they random
> writes?
overwrite=0 is even default. I'm thinking the "Laying out IO file"
message is confusing, it wont actually write contents first unless you
ask it to (with eg overwrite=1).
--
Jens Axboe
next prev parent reply other threads:[~2011-08-31 21:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-31 17:53 fio file test patterns Brian Fallik
2011-08-31 18:30 ` Jeff Moyer
2011-08-31 19:56 ` Jens Axboe
2011-08-31 20:34 ` Brian Fallik
2011-08-31 21:21 ` Jens Axboe
2011-08-31 21:38 ` Jens Axboe [this message]
2011-09-01 14:18 ` Brian Fallik
2011-09-01 16:06 ` Jens Axboe
2011-09-01 18:17 ` Brian Fallik
2011-09-01 20:14 ` Jens Axboe
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