linux-kernel - Re: [PATCH 00/14] Pramfs: Persistent and protected ram filesystem

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Message-ID: <20090628085932.GA20169@elf.ucw.cz>
Date:	Sun, 28 Jun 2009 10:59:32 +0200
From:	Pavel Machek <pavel@....cz>
To:	Marco Stornelli <marco.stornelli@...il.com>
Cc:	tim.bird@...sony.com, jamie@...reable.org,
	Linux Embedded <linux-embedded@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>,
	Daniel Walker <dwalker@....ucsc.edu>
Subject: Re: [PATCH 00/14] Pramfs: Persistent and protected ram filesystem

> >> > Ah now the write protection is a "needed feature", in your previous
> >> > comment you talked about why not use ext2/3.......
> >> >
> >> > Marco
> >> >
> >>
> >> Just for your information I tried the same test with pc in a virtual machine with 32MB of RAM:
> >>
> >> Version 1.03e       ------Sequential Output------ --Sequential Input- --Random-
> >>                     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> >> Machine   Size:chnk K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
> >> hostname     15M:1k 14156  99 128779 100 92240 100 11669 100 166242  99 80058  82
> >>                     ------Sequential Create------ --------Random Create--------
> >>                     -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> >>               files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
> >>                   4  2842  99 133506 104 45088 101  2787  99 79581 101 58212 102
> >>
> >> These data are the proof of the importance of the environment, workload and so on when we talk
> >> about benchmark. Your consideration are really superficial.
> >
> > Unfortunately, your numbers are meaningless.
> 
> I don't think so.
> 
> > (PCs should have cca 3GB/sec RAM transfer rates; and you demosstrated
> > cca 166MB/sec read rate; disk is 80MB/sec, so that's too slow. If you
> > want to prove your filesystem the filesystem is reasonably fast,
> > compare it with ext2 on ramdisk.)
> >
> This is the point. I don't want compare it with ext2 from performance
> point of view. This comparison makes no sense for me. I've done this
> test to prove that if you change environment you can change in a
> purposeful way the results.

Yes, IOW you demonstrated that the numbers are machine-dependend and
really meaningless.

ext2 comparison would tell you how much pramfs sucks (or not).
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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