[OE-core] [RFC] Performance Issue: Build time increases

[Lu, Lianhao]

Robert Yang wrote on 2011-08-12:
> 
> Hi folks,
> 
> The build time of core-image-sato increases about 5 ~ 10 minutes than
> the following commit:
> 
> commit 5af197b55a4b779f1ec93186f0723026949ba2b5
> Author: Liping Ke <liping.ke at intel.com>
> Date:   Fri Jun 3 08:22:40 2011 +0800
> 
>      cache: Implement multiple extra cache fields request support

I think this patch only stores extra information in an extra cache. It only affects the parsing time, and I don't think there will be 5 min difference. How about comparing the "bitbake -e" time with and without the patch(by deleting all the cache files before running bitbake).

Best Regards,
-Lianhao

> On my host,
> 1) the build time of 5af197b55a4b779f1ec93186f0723026949ba2b5 is:
> 
> real    208m26.133s
> user    241m29.280s
> sys     47m0.630s
> 
> 2) and: 068839698fe192d8846c0ed4db65861448e8e524 is:
> 
> real    217m39.687s
> user    255m34.150s
> sys     48m21.510s
> 
> 
> I use the bisect build method to find out which patch causes the time
> increases, but the build time is not stable on my host(Ubuntu 11.04
> 64bit), e.g., the build time of 1) is 208m at the first build, then
> "git co other_commit" and build it, after about 10 builds, then go
> back to build 5af197b55a4b779f1ec, the build time will increases about
> 8 minutes, I have stopped the X and cron, at. This may have relationship with the linux distribution and disk.
> 
> So I have to restart the build, reboot the machine by two days, and go
> on the build. It would be better if anyone has other good method.
> 
> I think that for the next release(e.g., yocto 1.2), we can find a
> clean and stable machine(for the distribution, maybe RHEL is more
> stable than Ubuntu) to check the build time weekly, so that we can notice the performance issue early.
>