Feedback for readahead

Armin Berres trigger+debian at space-based.de
Wed Jan 16 20:37:52 UTC 2008


On Wed, 16 Jan 08 09:43, Petter Reinholdtsen wrote:
> 
> [Armin Berres]
> > Yes, both files we're recreated on this box and I have neither /var/
> > nor /usr/ on a seperate partition.
> 
> This does not sound right.  Do the timestamp on both files indicate
> that they were updated during profile?  desktop should only be updated
> if /var/ or /usr/ are separate partitions.

Seems as if I was mistaken. I removed the files from /etc/readahead/ and
created an empty /etc/readahead/boot. After booting this file was empty
and I discovered, that readahead-watch was still running. What I found
out so far, is that no PID-file is availlable in /var/run/ and
readahead-watch isn't terminated therefore.
When I start and stop readahead from a console it works.
I have /boot/ on a seperate partition and / (with /usr/ and /var/ on the
same partition) is on LVM. Could this be the problem?

> Your bootchart did not look like the profiling had worked as it
> should.  If it had, no files should be read from disk after the
> readahead process was done.

I just retried with a recreated /etc/readahead/boot (I killed
readahead-watch by hand), but I didn't see an improvement.
BTW, what does readahead-watch do, while "Preparing to profile boot
sequence..."? I wonder why this takes between one or two minutes.

> > Could one win anything by preloading in the background and starting
> > e.g.  udev in the meanwhile? I have to admit that I have no idea if
> > this would make any sense wrt a short boot time.
> 
> Benchmarking done on Ubuntu indicated that running it the background
> was sligthly slower than running it in the foreground.  This is why it
> was changed to run in the foreground, and not in the background as it
> did initially.

OK, I see.

> OK.  I hope the preload package was not installed when you did the
> profiling.

Nope, I definitely don't have it installed.

Greetings,
Armin



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