linux-kernel - Re: WANTED: kernel projects for CS students

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] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.0711030300040.4780@asgard.lang.hm>
Date:	Sat, 3 Nov 2007 03:05:07 -0700 (PDT)
From:	david@...g.hm
To:	Rik van Riel <riel@...riel.com>
cc:	Valdis.Kletnieks@...edu,
	Lennart Sorensen <lsorense@...lub.uwaterloo.ca>,
	Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org
Subject: Re: WANTED: kernel projects for CS students

On Fri, 2 Nov 2007, Rik van Riel wrote:

> On Fri, 02 Nov 2007 23:08:23 -0400
> Valdis.Kletnieks@...edu wrote:
>
>> IBM's AIX supported file system compression on the JFS filesystem
>> years ago. I was able to get up to 30% throughput increases by
>> converting the /usr filesystem to compressed - because even a 33mhz
>> Power chipset could read in 5 512-byte blocks and decompress it to
>> the original 4K faster than the disk could read in 8 512-byte
>> blocks.
>
>> Given that today there's an even *bigger* disparity in CPU speed
>> versus disk speed, I'd be surprised if it doesn't help today too.
>
> The problem is that disk seek times have not gotten much
> faster over the years, while disk throughput rates have
> skyrocketed.
>
> Transferring a little less data is not going to help you
> when 80% of your disk time is spent seeking, not reading
> or writing.

however, if you can manage to avoid seeks by packing more data onto each 
track (or each stripe of a raid array) you could probably see a 
significant win

that's something for aspiring (and experianced) filesystem designers to 
struggle with for a while (especially trying to figure out what the size 
of a track or stripe is for the optimal layout)

David Lang
-
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/