[sr-dev] Small problems with make modules.. and a fix

[Andrei Pelinescu-Onciul]

On Feb 03, 2010 at 11:49, marius zbihlei <marius.zbihlei at 1and1.ro> wrote:
> Hello,
> 
> I want to make s/k modules with -j 3 . Thus specifying 3 parallel jobs 
> (Hehe I have one of those fancy SMP machines). The problem is this:
> 
> >make -j 3
> ....
> make[1]: Entering directory `/home/marius/dev/sip-router/modules/avpops'
> make[1]: warning: jobserver unavailable: using -j1.  Add `+' to parent 
> make rule.
> ....
> 
> Problem description is here 
> http://lists.samba.org/archive/distcc/2004q1/002160.html(I also checked 
> the gnu make manual and this mail is a rather complete copy-paste of the 
> section in question)
> 
> A description of the jobserver implementation in here 
> http://make.paulandlesley.org/jobserver.html.
> 
> The code in the Makefile which causes this is :
> 
> .PHONY: $(1)
> $(1): modules.lst
>    @for r in $($(1)) "" ; do \
>        if [ -n "$$$$r" -a -r "$$$$r/Makefile" ]; then \
>            $(call oecho, "" ;) \
>            $(call oecho, "" ;) \
>            if  $(MAKE) -C $$$$r $$(mk_params) || [ ${err_fail} != 1 ] ; 
> then \
>                :; \
>            else \
>                exit 1; \
>            fi ; \
>        fi ; \
>    done; true
> 
> Because I thought the problem might be with the for construct(make 
> launches a new shell) I have replaced this with
> 
> .PHONY: $(1)
> $(1): modules.lst
>    @$(foreach r,$($(1)),$(call module_make,$(r),$(mk_params)))
> 
> And in Makefile.rules I've added
> 
> module_make=    if [ -n "$(1)" -a -r "$(1)/Makefile" ]; then \
>            $(call oecho, "" ;) \
>            $(call oecho, "" ;) \
>            ( $$(MAKE) -C $(1) $(2) || [ ${err_fail} != 1 ] )  || exit 1; \
>        fi ; \
> 
> This fixed the warning and multiple make jobs work fine now with make 
> modules.
> 
> So. Do I push?!

I like it, but the problem is that it might be slower for -j1. This way you
launch one different shell for each module (in fact 2 shells, the () arround
  $$(MAKE)...  launch another subshell). The old way launched everything
into the same subshell.
We could try 2 different versions, one for no -j or -j1 and one for -jX
(looking at the make command line to decide which one to use).

Andrei