From: Jens Axboe <axboe@kernel.dk>
To: Matthew Eaton <m.eaton82@gmail.com>
Cc: fio@vger.kernel.org
Subject: Re: Possible bug when setting compression
Date: Fri, 14 Mar 2014 19:39:51 -0600 [thread overview]
Message-ID: <5323AF67.4090906@kernel.dk> (raw)
In-Reply-To: <CAF+0mvmL6hmFkm2Tf__EYz=PUceEX=H4NURb9bm1_hY_XTmXVQ@mail.gmail.com>
On 2014-03-14 16:26, Matthew Eaton wrote:
>> scramble_buffers tells fio to randomly insert some data in the buffer. It's
>> not a full overwrite or anything like that, just some basic garbage for each
>> 512b to prevent naive compression/dedupe.
>>
>> --
>> Jens Axboe
>>
>>
>
> Thanks, that makes sense. I guess my only concern is one might expect
> that setting zero_buffers alone would provide fully compressible data,
> not realizing that scramble_buffers is still adding some random data
> unless explicitly turned off.
>
> Maybe something that could be added to the man page / how to under
> zero_buffers? Something like...
>
> "If you want a fully compressible workload, also set scramble_buffers=0."
Sure, we can add that to make it completely clear.
--
Jens Axboe
prev parent reply other threads:[~2014-03-15 1:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-14 15:52 Possible bug when setting compression Matthew Eaton
2014-03-14 18:26 ` Jens Axboe
2014-03-14 19:45 ` Matthew Eaton
2014-03-14 20:09 ` Jens Axboe
2014-03-14 20:23 ` Jens Axboe
2014-03-14 20:53 ` Matthew Eaton
2014-03-14 20:56 ` Jens Axboe
2014-03-14 21:06 ` Matthew Eaton
2014-03-14 21:33 ` Jens Axboe
2014-03-14 22:26 ` Matthew Eaton
2014-03-15 1:39 ` Jens Axboe [this message]
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