Multi-Threaded make

[John Wendel]

On 11/28/2012 08:16 PM, JD wrote:
>
> On 11/28/2012 08:21 PM, Cameron Simpson wrote:
>> On 28Nov2012 15:37, JD <jd1008 at gmail.com> wrote:
>> | While building the kernel from source RPM, I run
>> | the command ps -ef | grep make in another terminal,
>> | and I do see that 4 make processes are running, with
>> | each one building objects for a different kernel source
>> | directory.
>> |
>> | However, something else seems to be single threaded
>> | which is causing the huge delay in finishing kernel build.
>> |
>> | I found that when I run top to see the upper-most
>> | cpu consumers, I see only one cc1 process at the top.
>> |
>> | So I ran ps again to see how many cc1 processes there
>> | are.
>> |
>> | Always - just one cc1 process.
>> |
>> | I would expect to see anywhere from 1 to 4 cc1 processes
>> | at a time. But that is not the case.
>> |
>> | What is forcing only a single instance of cc1 at a time?
>>
>> Is make running with the "-j 4" (or whatever value) option?
> I had already said that after running rpmbuild,
> ps -ef shows 4 make processes running.
> So, it must be picking up -j4 from somewhere,
> perhaps from one of the rpmbuild macros.
>
> But as I also stated, when files are being compiled, one of the stages
> of compilation is cc1. Since there are 4 make processes running at a 
> time,
> with each make process running for one of the dirs containing kernel c
> source files, then one woould expect to see anywhere from 1 to cc1
> processes running during the build.
> I only see a single cc1 process running during the entire kernel build 
> duration,
> by running ps -ef  | grep cc1
> every 5 seconds.
>
> I never see more than a single instance of cc1.
>

I can't help with this question, but I build a new kernel (from 
kernel.org) whenever they appear.
This never takes more than 5 or 6 minutes on a slow 2-cpu AMD box with 
only 1 GB memory.  I usually
don't specify "-j", so I only have one process running.

I think you're seeing something seriously broken if your builds are 
taking a huge amount of time.

Regards,

John