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From: "Elliott, Robert (Server Storage)" <Elliott@hp.com>
To: "Kudryavtsev, Andrey O" <andrey.o.kudryavtsev@intel.com>,
	Andrey Kuzmin <andrey.v.kuzmin@gmail.com>
Cc: "fio@vger.kernel.org" <fio@vger.kernel.org>
Subject: RE: REPORT: FIO random read performance degradation without "norandommap" option
Date: Mon, 12 Jan 2015 22:56:23 +0000	[thread overview]
Message-ID: <94D0CD8314A33A4D9D801C0FE68B40295A732BE0@G9W0745.americas.hpqcorp.net> (raw)
In-Reply-To: <D0D9732D.107AC%andrey.o.kudryavtsev@intel.com>



> -----Original Message-----
> From: Kudryavtsev, Andrey O [mailto:andrey.o.kudryavtsev@intel.com]
> Sent: Monday, 12 January, 2015 3:06 PM
> To: Andrey Kuzmin
> Cc: Elliott, Robert (Server Storage); fio@vger.kernel.org
> Subject: Re: REPORT: FIO random read performance degradation without
> "norandommap" option
> 
> Hi Andrey,
> Thank you, it explains the purpose of this feature. Unfortunately it was
> not clear to me from the manual, I faulty supposed it increases the
> randomness of the random generator distribution. Thanks again!
> 
> I’d propose to have it auto set to "norandommap" if “randread” workload is
> specified. Does it make sense?
> 

I don't think I'd change it.  For randread, randommap ensures that each
LBA has been accessed once before it repeats reading any of the LBAs. That
could be useful in some cases, like scanning the media (ensuring you've
read each LBA).

---
Rob Elliott    HP Server Storage



  reply	other threads:[~2015-01-12 22:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-09 22:42 REPORT: FIO random read performance degradation without "norandommap" option Kudryavtsev, Andrey O
2015-01-09 22:49 ` Elliott, Robert (Server Storage)
2015-01-09 23:01   ` Kudryavtsev, Andrey O
2015-01-10  9:20     ` Andrey Kuzmin
2015-01-12 21:06       ` Kudryavtsev, Andrey O
2015-01-12 22:56         ` Elliott, Robert (Server Storage) [this message]
2015-01-09 23:07   ` Kulkarni, Vasu

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