From: Jens Axboe <axboe@kernel.dk>
To: Carl Zwanzig <cpz@coraid.com>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: Re: Generating almost-sequential traffic
Date: Thu, 27 Jun 2013 11:01:23 +0200 [thread overview]
Message-ID: <20130627090123.GK25599@kernel.dk> (raw)
In-Reply-To: <A7A1D348E34E024BBC74480FB93A2EAB039C63@DAGN05A-E6.exg6.exghost.com>
On Wed, Jun 26 2013, Carl Zwanzig wrote:
> Hi,
>
> I need to test some devices with "almost-sequential" data traffic. This would have anywhere from 10 to 50 I/Os in order then either drop one from the sequence "1 2 3 (no 4) 5 6" or transpose two adjacent ones "1 2 (4 3) 5 6". This could be done with an iolog, but that seems both wasteful (huge files, 131k lines/MB) and slow (for reading and processing the files). To properly test, I need to move something like 3-4 Tb in 8k blocks.
>
> It's also inelegant :).
>
> It looks like a drop sequence can be done with something like:
> blocksize=64k
> rw=write:8k
> but I'm at a loss for how to do transposition. Could be a hack into the get-next-block code in io_u.c, but I don't see how to actually implement that.
>
> Any ideas (or is an iolog the best way)?
See percentage_random in the man page (or --cmdhelp=percentage_random)
--
Jens Axboe
next prev parent reply other threads:[~2013-06-27 9:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 22:31 Generating almost-sequential traffic Carl Zwanzig
2013-06-27 9:01 ` Jens Axboe [this message]
2013-06-27 17:41 ` Carl Zwanzig
2013-06-27 19:28 ` Jens Axboe
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