Re: [Fedora-livecd-list] Woohoo! 31% boot speedup (*so far*), and 4.5MB free...

[Douglas McClendon <dmc fedora filteredperception org>]

Just a status report on this, since 31% is such an outlandish claim...

I'm currently investigating why it is that my find atime command on my 
livecd typically shows about 20k/80k files accessed during a normal 
boot, versus 3k/80k on the f8 livecd.  If anyone would like to venture 
speculation or facts as to which of those numbers is more realistic... 
Looking at the diffs, I know that 3k is missing some stuff, like, 
/etc/xdg/menus (the directory entry) not showing up, even though files 
under the directory show up.  And I did extract the initramfs from the 
f8 livecd, change it's /etc/fstab, initramfs /init, and 
/sysroot/etc/fstab to all have atime,diratime instead of noatime and/or 
relatime.  And I echod 0 to /proc/sys/fs/default_relatime as soon as 
proc was mounted.

( find / -xdev -atime -7 -exec ls -ld '{}' ';' > boot.afiles.list.txt )

Anyway, I still think I can get significant improvement, but there are a 
lot of experiments and trials to run.

In general, I'm also going to try ordering the filesystem with all 
directory entries together, and symlinks together, to see how that helps 
compression.  Likewise all text files, and all these things alpha and 
size sorted.  I'm particularly interested if anyone has speculation as 
to why clustering the directory entries and symlinks might be some bad 
cornercase for ext3 filesystem performance.

And unfortunately I can't get the dm-reverse kernel module to compile 
easily (don't think anyone's actually used it in years).  But I may go 
back to my own kludge, somewhat similar to the perl extent reversing 
example in the dm docs.

I'll let you all know how it goes...  Maybe nowhere, maybe it'll speed 
up boot 50% and make space for another 10MB of compressed stuff...

-dmc


Douglas McClendon wrote:
> Douglas McClendon wrote:
> ...
> > Thus, what I tenatively see, beyond the 4.5M of free space, is a 31% 
> > speedup (203s/154s)
> >
> > So, going forward, I plan to
> >
> > [1]A) do some sick stuff to get those early files on the outter rim of 
> > the cdrom, which I think may get further significant gains by itself, 
> > and perhaps even push my SDMC method into the significantly profitable 
> > area (though I don't much care at this point).
>
> And here I was thinking of doing my own kludge, but yet AGAIN, Device 
> Mapper Is Just So Cool - (dm-reverse)
>
> http://sources.redhat.com/cgi-bin/cvsweb.cgi/device-mapper/contrib/?cvsroot=dm 
>
>
> -dmc
>
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