CD/DVD building on farbror
I'm in the middle of moving the weekly builds to farbror too. As I
suggested to some people a while ago, running the CD and DVD builds in
parallel for each architecture might have some benefit. Farbror has
plenty of CPU and disk bandwidth during the build phase, and enough
RAM that it should be able to cache large amounts of the data.
So, this needed to be tested! I got the following output from running
test builds on an otherwise (mostly) idle system.
Sat Nov 25 04:21:12 CET 2006
Making i386 dvds in /home/deb-cd/build/debian-cd.dvd/../out/3i386 (/home/deb-cd/build/debian-cd.dvd/../out/3i386/i386/jigdo-dvd)
Missing package file for arch hurd-i386.
Missing package file for arch sh.
i386 DVDs started at 03:21:12, ended at 03:55:15
...
At revision 1201.
At revision 1201.
Sat Nov 25 05:01:31 CET 2006
Making i386 dvds in /home/deb-cd/build/debian-cd.dvd/../out/3i386 (/home/deb-cd/build/debian-cd.dvd/../out/3i386/i386/jigdo-dvd)
Missing package file for arch hurd-i386.
Missing package file for arch sh.
Making i386 cds in /home/deb-cd/build/debian-cd/../out/i386 (/home/deb-cd/build/debian-cd/../out/i386/i386/jigdo-cd)
Missing package file for arch hurd-i386.
Missing package file for arch sh.
i386 DVDs started at 04:01:31, ended at 05:08:41
i386 CDs started at 04:01:31, ended at 05:08:51
A single DVD build took 34m03s, while running both CD and DVD in
parallel took 67m20s. Each CD and DVD build should be just about
equivalent in terms of the amount of work needed (look at the times
for the parallel run). Therefore I'd expect DVD followed by CD
serially to take ~68m or so.
Running in parallel doesn't seems to gain us much (less than 1%, so
lost in the noise tbh), but equally it's not slower, which might have
been the case. Ah well, this is why we test things. :-)
For (some) reference, the last full i386 CD build on bla took 56m36s
for a smaller task. Why smaller? On bla we just built jigdo files,
then synced those jigdo files to farbror for rebuild into ISO
files. On farbror, we're incurring the extra disk bandwidth hit of
building ISO files alongside the jigdo files. So, it's capable of
running *2* bigger builds in parallel than 1 small one on bla in ~20%
more time, or 1 bigger build in ~40% less time. W00t! The total
end-to-end time for a full CD/DVD run should also be substantially
reduced, as we no longer need to do the jigdo-to-iso step either.
--
Steve McIntyre, Cambridge, UK. steve@einval.com
"I can't ever sleep on planes ... call it irrational if you like, but I'm
afraid I'll miss my stop" -- Vivek Dasmohapatra
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