[yocto] Build time data

[Martin Jansa]

On Thu, Apr 12, 2012 at 11:08:19PM -0700, Darren Hart wrote:
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> On 04/12/2012 10:51 PM, Martin Jansa wrote:
> 
> > And my system is very slow compared to yours, I've found my
> > measurement of core-image-minimal-with-mtdutils around 95 mins 
> > http://patchwork.openembedded.org/patch/17039/ but this was with
> > Phenom II X4 965, 4GB RAM, RAID0 (3 SATA2 disks) for WORKDIR, RAID5
> > (the same 3 SATA2 disks) BUILDDIR (raid as mdraid), now I have
> > Bulldozer AMD FX(tm)-8120, 16GB RAM, still the same RAID0 but 
> > different motherboard..
> 
> Why RAID5 for BUILDDIR? The write overhead of RAID5 is very high. The
> savings RAID5 alots you is more significant with more disks, but with
> 3 disks it's only 1 disk better than RAID10, with a lot more overhead.

Becaure RAID10 needs at least 4 drivers and all my SATA ports are
already used and also it's on my /home partition.. please not that this
is not some company build server, just my desktop where it happens I do
a lot of builds for comunity distribution for smartphones
http://shr-project.org

Server we have available for builds is _much_ slower then this
especially IO (some virtualized host on busy server), but has much
better network bandwidth.. :).

Cheers,
 
> I spent some time outlining all this a while back:
> http://www.dvhart.com/2011/03/qnap_ts419p_configuration_raid_levels_and_throughput/
> 
> Here's the relevant bit:
> 
> "RAID 5 distributes parity across all the drives in the array, this
> parity calculation is both compute intensive and IO intensive. Every
> write requires the parity calculation, and data must be written to
> every drive."
> 
> 
> 
> - --
> Darren Hart
> Intel Open Source Technology Center
> Yocto Project - Linux Kernel
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-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa at gmail.com
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