Re: [Devil-linux-develop] default options suggestions

[Andrzej O. <an...@ma...>]

Heiko Zuerker wrote:
>>1. In build configuration option CONFIG_PMAKE in make menuconfig has
>>    a limit of 2. I observed on my Core Quad that compilation is faster
>>    when CONFIG_PMAKE=4. I think, better is set this limit to 4.
> Many programs have trouble with this, that's why we limited it to 2.
> DL 1.3 has a better options which is much more stable.
I'm not sure, we are talking about this same? I think about build process of 
last DL 1.3 development and about setting in "Build Configuration" | "Parallel 
Compile Jobs" which is recorded as CONFIG_PMAKE option in build/.config and 
limits number of cc compilations simultaneously. This option is transferred 
mainly to -j parameter of make command when compiling kernel or packages.

I understand that more then 2 cc parallel processes on single CPU enhances 
process scheduling overdraft and sometimes is slower, than one process after 
one. And 4 parallel processes on single CPU can be much slower.

But on 4 CPU cores in compiling/building machine if I set CONFIG_PMAKE option 
to 4, complete build from unpack to iso take 2h30' but if this option allows 
only 2 cc processes simultaneously, total time is over 3h.

I unterstand difference between one and two processes, because in parallel 
computing coprocesses must be independent or synchronised. But if You allow 
for 2 parallel processs, what difference for 4 parallel cc's? I think cc 
processes are from definition independent.

But, if You are sure You know about negative experience with parallel 
compilations, OK. I accept this. I work in computer science from 70s 
(beginning from CDC Cyber 7000) and I know many miracles in computing. :-)

Regards

Andrzej Odyniec