[yocto] Shorter build time?

[Takashi Matsuzawa]

Hello Yocto.

Well, this may not be a very new topic, but I wonder if you have recent suggetions.
So far I have tried the followings and see some improvement, making the build time to days to hours.

1) All of the directories, DL_DIR, SSTATE_CACHE, TMPDIR, DEPLOY_DIR are on SSD.
2) .repo and working directory (where I synch my recipes) also on SSD.
3) Set BB_NUMBER_PARSE_THREADS/PARALLEL_MAKE/BB_NUMBER_THREADS to something like 20, 30, etc.
4) Enable use of ICECC.
5) Use pigz, pbzip2, pxz instead of gzip, bzip2 and xz.

I can see with 3-5), I am benefited from my multicore PCs and see some scaling effects (if I can add more PCs or CPU core.)
However I think there is i the build not paralleled or distributed easily.

i) python tasks
They say python has slimitation of being single thread, and could be a bottle neck since most of yocto build tasks are in python, if not native/cross toolchain jobs.

ii) zip / tar tasks
e.g. seeing rootfs taking forever, jobs not distributed to the other machines.
I understand it is writing files to one target tree and doing a bit tar/zip for the files, being one big job though.

I wonder if I can do anything with i) and ii) at least to make them processed in parallel.
ICECC only can dispatch gcc jobs I believe.
Any previous attemps to do the similar to non-gcc jobs?