[U-Boot] [PATCH v8 0/38] Switch over to real Kbuild

[Tom Rini]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 02/18/2014 04:02 AM, Masahiro Yamada wrote:
> Hello Simon,
> 
> 
>> 
>> I'm not sure whether to start a new thread or not, but here in
>> one observations which might be useful.
>> 
>> With current master, a 'null' build (with nothing changed) takes
>> about 5s for me.
>> 
>> time
>> CROSS_COMPILE=/opt/linaro/gcc-linaro-arm-linux-gnueabihf-4.8-2013.08_linux/bin/arm
>>
>> 
- -linux-gnueabihf- ARCH=arm make -j1
>> real 0m4.978s user 0m1.144s sys 0m0.360s
>> 
>> 
>> With the kbuild series, it takes a lot longer:
>> 
>> real 0m46.600s user 0m17.628s sys 0m8.664s
> 
> Thanks for your feedback.
> 
> Hmm, Kbuild is 9 times slower on your computer. This is a big
> difference. (It was about 1.6 x slower on my box.)
> 
> I don't know where such a difference came from.
> 
>> There seem to be noticeable pauses between things happening. I'm
>> not quite sure how to dig into it more. Is it possible that
>> cc-option is no-longer caching the various compiler options?
> 
> I guess it's possible.
> 
> Is sandbox build slow as well? Sandbox has no cc-option. If
> cc-option is the cause of pauses, sandbox build should be faster.
> 
> Anyway, evaluating cc-option multiple times isn't nice and its
> optimization is on my TODO list.

Can we move this up on the TODO list please?  Some quick testing
around here says that this is the big culprit on build times.  I get
pre-Kbuild series build time to match post-Kbuild series by building
with CONFIG_CC_OPT_CACHE_DISABLE=y.

- -- 
Tom
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
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=gu7X
-----END PGP SIGNATURE-----