FYI: what it takes for RAM+swap to build devel/llvm40 with 4 processors or cores and WITH__DEBUG= (powerpc64 example)

[Mark Millard]

On 2017-Mar-27, at 3:25 AM, Mark Millard <markmi at dsl-only.net> wrote:

> On 2017-Mar-27, at 2:41 AM, Dimitry Andric <dim at FreeBSD.org> wrote:
> 
>> On 26 Mar 2017, at 23:36, Mark Millard <markmi at dsl-only.net> wrote:
>>> 
>>> I upgraded from llvm40 r4 to final. An interesting result was
>>> its creation of a backup package for llvm40-4.0.0.r4:
>>> 
>>> about 13 cpu-core-hours running pkg create
>>> 
>>> (Remember: I've been building with WITH_DEBUG= ) Its
>>> single-threaded status stands out via elapsed time
>>> approximately matching.
>>> 
>>> I'll note that it was somewhat under 6 elapsed hours for
>>> staging to have been populated (-j4 with 4 cores present
>>> helps for this part).
>>> 
>>> (Of course these elapsed-time figures are rather system
>>> dependent, although the ratio might be more stable.)
>>> 
>>> 
>>> 
>>> Also interesting was:
>>> 
>>> Installed packages to be REMOVED:
>>> 	llvm40-4.0.0.r4
>>> 
>>> Number of packages to be removed: 1
>>> 
>>> The operation will free 49 GiB.
>> 
>> Yes, this is big.  But there is no real need to build the llvm ports
>> with debug information, unless you want to hack on llvm itself.  And
>> in that case, you are better served by a Subversion checkout or Git
>> clone from upstream instead.
>> 
>> -Dimitry
> 
> FYI:
> 
> Historically unless something extreme like this ends up
> involved I build everything using WITH_DEBUG=  or explicit
> -g's in order to have better information on any failure.
> 
> This is extreme enough that next time I synchronize
> /usr/ports and it has a devel/llvm40 update I'll
> likely rebuild devel/llvm40 without using WITH_DEBUG= .
> I'm more concerned with the time it takes than with
> the file system space involved.

[Bad example of a incomplete thought. . .]

That last presumes a hardware environment with lots
of RAM (such as 16 GiBytes) --which I usually do not
have access to. Having such is why the report was
from a powerpc64 context: that is where I've access
to that much RAM for FreeBSD.

===
Mark Millard
markmi at dsl-only.net