linux-kernel - Re: RAID-1 performance under 2.4 and 2.6

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e2e108260803280044o1bf41e5q8fd0b00a772b54a4@mail.gmail.com>
Date:	Fri, 28 Mar 2008 08:44:37 +0100
From:	"Bart Van Assche" <bart.vanassche@...il.com>
To:	"Bill Davidsen" <davidsen@....com>
Cc:	"Chris Snook" <csnook@...hat.com>,
	"Emmanuel Florac" <eflorac@...ellique.com>,
	linux-kernel@...r.kernel.org
Subject: Re: RAID-1 performance under 2.4 and 2.6

On Thu, Mar 27, 2008 at 10:53 PM, Bill Davidsen <davidsen@....com> wrote:
> Bart Van Assche wrote:
> > On Tue, Mar 25, 2008 at 11:00 PM, Chris Snook <csnook@...hat.com> wrote:
> >>  It means you shouldn't use dd as a benchmark.
> >
> > If you want to benchmark write speed, you should add
> > oflag=direct,dsync to the dd command line. For benchmarking read speed
> > you should specify iflag=direct. Or, even better, you can use xdd with
> > the flags -dio -processlock.
>
>  No, you want your benchmark to measure performance doing what the
>  application does. Do unless you have an application which has been
>  heavily Linux-ized you don't want to measure something unrelated to the
>  application requirements.

A basic fact I learned in science classes: if you measure something,
know very well what you measure and make sure your measurement is
repeatable. But it was some time ago I learned this. Maybe the whole
world changed since I learned that ?

Bart.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/