Re: [OSR-devel] Speeding up mkinitrd

[Marc G. <gr...@at...>]

On Friday 13 February 2009 19:42:42 Gordan Bobic wrote:
> Gordan Bobic wrote:
> > 2) Compression speed
> >
> > 2.1) Using a parallel gzip (http://www.zlib.net/pigz/) compressor, which
> > should scale pretty much linearly with the number of CPU cores. A
> > (source) RPM seems to be available, but only for SuSE
> > (http://rpm.pbone.net/index.php3/stat/4/idpl/11044884/com/pigz-2.1.4-5.1.
> >x86_64.rpm.html), so until it is more common, it may have to be made
> > available via the comoonics yum repository.
>
> OK, that was 100% pain-free. The SuSE src.rpm compiles cleanly on
> RHEL/CentOS 5.x. The performance scaling is completely linear (32
> seconds with gzip on a quad core Core2, 8 seconds using pigz).
;-)
>
> The resulting compressed files aren't identical (pigz one is actually a
> tiny bit smaller), but when they are ungzipped (ungzipping works using
> standard ungzip), the decompressed files are the same, so it seems safe
> enough. :)
>
> Even without any further boosts in compression speed, this seems pretty
> worthwhile, and it has the advantage of being 100% clean, OSS, and
> extremely painless to implement (whereas ICC will involve opening a
> whole new can of worms for a much smaller benefit).
>
> So, if I may be so bold to ask - any chance of including pigz in the yum
> repository and adding a dependency on it for the comoonics-bootimage?
>
> I'd submit a create-gfs-initrd-lib.sh patch, but I can't help but feel
> that a patch as small as 2 lines would be a bit lame. :^)
That's no problem. I will make a variable for the compression program that can 
be overwritten in /etc/comoonics/bootimage/bootimage.cfg.
And yes that's only two lines.

The more dramatic speed up I'm thinking about is the one with using only one 
rpm process and dieting wherever possible and wherever needed. This reduces 
the size of initrd and consequently the time for compressing it.

But I need to check if the filters are compatible with that concept. If so 
that should be pretty easy if not the filters have to be rewritten. Which 
should also be possible.

I'll give feetback.

Marc.


-- 
Gruss / Regards,

Marc Grimme
http://www.atix.de/               http://www.open-sharedroot.org/