Re: kernel module parallel build?

On 5 Dec 2012, at 18:39, Warner Losh <imp_at_bsdimp.com> wrote:

> 
> On Dec 5, 2012, at 9:42 AM, John Baldwin wrote:
> 
>> On Tuesday, December 04, 2012 2:41:32 pm Ryan Stone wrote:
>>> On Tue, Dec 4, 2012 at 10:52 AM, John Baldwin <jhb_at_freebsd.org> wrote:
>>> 
>>>> Hmm, I certainly see the module directories being built in parallel.  Some
>>>> of
>>>> the make jobs may not be as obvious since links are silent (no output
>>>> unless
>>>> there is an error).
>>>> 
>>>> 
>>> This is definitely not the behaviour that I see trying to build any version
>>> of FreeBSD.  I see the same behaviour as Andre: the depend and all targets
>>> both iterate through the module directories sequentially.  It never builds
>>> two module subdirectories concurrently.
>> 
>> Hmm, I think I was confused by seeing kernel builds intermingle with the 
>> associated modules.  sys/modules/Makefile uses bsd.subdir.mk.  I think I see 
>> similar things in world builds where I will see parallel builds of bin vs sbin 
>> vs usr.bin vs usr.sbin, but within each of those directories the builds go 
>> sequentially.  I think you would need to change bsd.subdir.mk if you want to 
>> fix this.
> 
> The builds are in parallel, just that the parallelism is low because it is only parallel within the module being built. Would love to see a fix.
> 
> Warner
> 

All trolling aside, I believe an awesome fix to be setting module override in /etc/make.conf to only build the 4-5 specific modules one needs.

To be honest I think this configuration tweak should be advertised a bit more as it definitely speeds up kernel builds.

I would be happy to check if this is advertised in the handbook in the "rebuilding kernel" section and enhance its visibility if required.

I can provide en_US and fr_FR.