Re: [Boost-build] Programmatic Job Count

Subject: Re: [Boost-build] Programmatic Job Count
From: Vladimir Prus (vladimir_at_[hidden])
Date: 2008-11-21 04:24:18

Johan Nilsson wrote:

> Phillip Seaver wrote:
>> Vladimir Prus wrote:
>>> On Wednesday 19 November 2008 11:16:00 you wrote:
>>>
>>>> On Tuesday 18 November 2008 21:04:38 Brad Howes wrote:
>>>>
>>>>> Is there any way to tell Boost how many jobs to run in parallel
>>>>> from within a Jamfile, a programmatic equivalent to '-j N'?
>>>>>
>>>> It is not possible, but hopefully will be possible later today :-)
>>>>
>>>
>>> Brad,
>>>
>>> Please update and rebuild Boost.Jam. Then, put the following in your
>>> Jamroot:
>>>
>>> import modules ;
>>> modules.poke : PARALLELISM : 4 ;
>>>
>>> and it should have the same effect as -j4 on command line.
>>> Presently, the PARALLELISM variable overrides -j option. Soonish,
>>> I'll make it so:
>>>
>>> - you can create file project-config.jam, containing:
>>>
>>> option jobs : 4 ;
>>>
>>> and have 4 jobs by default
>>>
>>> - you can use --jobs=10 on command like, overriding
>>> project-config.jam
>>>
>>> Let me know if the Boost.Jam change works for you, and if the future
>>> directions seems right,
>>>
>>> Thanks,
>>> Volodya
>>
>> That's cool, Volodya.  Will that work from site-config.jam?  That
>> seems
>> a logical place to use it for those of us that use machines with
>> different numbers of processors.  We have 2-, 4-, and 8-core machines
>> that we regularly build on, so it would make more sense (for us) to
>> make
>> it machine-specific.
> 
> Not necessarily; on our build machines we're likely to compile unrelated
> Boost.Build projects concurrently, and would rather like to allocate e.g. 2
> execution units for one of the projects and 2 for the other.
> 
> Using project-config makes lots of sense for those of us that regularly work
> on several projects at the "same time". However, I agree that it should be
> possible to specify parallellism in site-config as well (or user-config, for
> that matter).
> 
> I would guess that Volodya has already thought about this (and perhaps
> described it in this mailing list), but the precedence for options set in
> config files should probably be (highest to lowest):
> 
> project-config
> user-config
> site-config

Yes, that's the plan (at least for the parallelisation option). 

- Volodya