Messages in this thread | | | Date | Sat, 3 Nov 2007 03:05:07 -0700 (PDT) | From | david@lang ... | Subject | Re: WANTED: kernel projects for CS students |
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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/
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