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From: Jun He <jhe@cs.wisc.edu>
To: Sitsofe Wheeler <sitsofe@gmail.com>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: io_size usage
Date: Thu, 10 Dec 2015 09:14:56 -0600	[thread overview]
Message-ID: <CABW1wHSc9aJsxus4SEQz8So7ccCSAd9HwHRmNUeoR+3ff1+Vsw@mail.gmail.com> (raw)
In-Reply-To: <CALjAwxgQwgrQbd9EeuRtqnmo5WrPoXk=HVuQ2nnuwgJ=9kDqOw@mail.gmail.com>

Thanks for the mentioning the 'loops' option.

But still, it is weird that by changing ioengine, iolog will report differently.
I think either sync mistakenly performs only one loop, or the IO is done
correctly but iolog report is wrong.

I think the expected behavior is that iolog is the same for both sync and
libaio. And both of them should follow the HOW:

"if 'size' is set to 21G, and 'io_size' is set to 40G, then fio will do 40G of
IO within the 0..20G region."


Jun




On Thu, Dec 10, 2015 at 12:56 AM, Sitsofe Wheeler <sitsofe@gmail.com> wrote:
> Hi,
>
> Your job sets and io_size four times that of "size" of the disk that
> you are using. This will force your I/O to wrap abound to the start of
> the region (why not use loops?). Are you saying that you think the
> sync job's iolog is wrong because it only says it performed one loop?
>
> On 9 December 2015 at 02:50, Jun He <jhe@cs.wisc.edu> wrote:
>> Hi all,
>> I think there is a bug for io_size.
>>
>> For example, I want to write 16KB data to a file of size 8KB (so each block is
>> written twice) and I have the following job file:
>>
>> [global]
>> ioengine=sync
>> rw=write
>> bs=4kb
>> size=8kb
>> io_size=32kb
>>
>> [job1]
>> write_iolog=iolog.1
>>
>>
>> After running, iolog.1 will contain the following contents:
>>
>> fio version 2 iolog
>> job1.0.0 add
>> job1.0.0 open
>> job1.0.0 write 0 4096
>> job1.0.0 write 4096 4096
>> job1.0.0 close
>>
>> This shows that each block has been only written once.
>>
>> If I change the ioengine to libaio, iolog.1 will contain:
>>
>> fio version 2 iolog
>> job1.0.0 add
>> job1.0.0 open
>> job1.0.0 write 0 4096
>> job1.0.0 write 4096 4096
>> job1.0.0 close
>> job1.0.0 open
>> job1.0.0 write 0 4096
>> job1.0.0 write 4096 4096
>> job1.0.0 close
>> job1.0.0 open
>> job1.0.0 write 0 4096
>> job1.0.0 write 4096 4096
>> job1.0.0 close
>> job1.0.0 open
>> job1.0.0 write 0 4096
>> job1.0.0 write 4096 4096
>> job1.0.0 close
>>
>>
>> Bug or wrong usage?
>>
>> Thanks,
>> Jun
>>
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe fio" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>
> --
> Sitsofe | http://sucs.org/~sits/

      reply	other threads:[~2015-12-10 15:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-09  2:50 io_size usage Jun He
2015-12-10  6:56 ` Sitsofe Wheeler
2015-12-10 15:14   ` Jun He [this message]

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