Speeding up live cd boot through optimizing file layout

[Matt Zimmerman]

On Wed, May 31, 2006 at 11:24:11AM +0200, Krzysztof Lichota wrote:
> Matt Zimmerman napisał(a):
> > On Tue, May 30, 2006 at 11:22:37AM +0200, Krzysztof Lichota wrote:
> >> Matt Zimmerman napisał(a):
> >>> The above was written in response to a proposal to move the single most
> >>> frequently accessed file to the edge of the disk; what you are describing is
> >>> something quite different: grouping the files read at boot in one place on
> >>> the disc.
> >>>
> >>> This, in fact, has a reasonable chance of improving performance, since all
> >>> of these files are read in a single pass by /etc/init.d/readahead.
> >> Interesting. I will try moving these files to the end of Squashfs image.
> > 
> > In case you didn't know, this data can be found in /etc/readahead, in
> > exactly the order used for readahead during startup.
> 
> I have tried putting these files at the edge and the results are 10
> seconds worse. Apparently seeks are more frequent and throughput is not
> an issue.

How interesting.  Did you ensure that the list is up to date?  If it is, it
should be ordered according to the actual order in which files are read at
boot, so there should be no other I/O happening in parallel to cause
additional seeks.  Does the system have enough memory to cache all of the
files there?

-- 
 - mdz