Re: [PATCH 2/3] ci: do not use #processors+1 jobs, #processors is enough

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/05/21 12:49, Thomas Huth wrote:
>>
>> -    - JOBS=$(expr $(nproc) + 1)
>> +    - JOBS=$(nproc || echo 1)
> 
> The basic idea of the "+ 1" was to make sure that there is always a 
> thread that runs on a CPU while maybe another one is waiting for I/O to 
> complete.

Ah, I see.  It doesn't make much sense for "make check" jobs however, 
which is where I wanted to get with the next patch.

I'm not sure it's even true anymore with current build machines (which 
tend to have a large buffer cache for headers) and optimizing compilers 
that compilation is I/O bound, so I'll time the two and see if there is 
an actual difference.

Paolo

  This is suggested by various sites on the web, e.g.:
> 
> https://unix.stackexchange.com/questions/519092/what-is-the-logic-of-using-nproc-1-in-make-command 
> 
> So not sure whether this patch here make sense ... I'd rather drop it.