lkml.org 
[lkml]   [2007]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 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@vt.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@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-11-03 10:59    [W:0.751 / U:0.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site