________________________________
From: Satish Balay <[email protected]>
Sent: Tuesday, July 24, 2018 4:06 PM
To: Fande Kong
Cc: Jed Brown; For users of the development version of PETSc
Subject: Re: [petsc-dev] could we let "make -j N" work for PETSc and external
packages?
PETSc configure sets up a default value that always gets used.
>>>>>>>
balay@asterix /home/balay/tmp/petsc (maint=)
$ make
<snip>
Using MAKEFLAGS: -j4 -l6.0 w -- PETSC_DIR=/home/balay/tmp/petsc
PETSC_ARCH=arch-linux2-c-debug
<<<
You can always override this default by adding a -j option. [since the
user specified -j value comes at the end - it overrides the one that
is specified at the begining of make command]
>>>>>>>>>>
balay@asterix /home/balay/tmp/petsc (maint=)
$ make -j20
<snip>
Using MAKEFLAGS: -j4 -l6.0 w -j20 --jobserver-auth=3,4 --
PETSC_DIR=/home/balay/tmp/petsc PETSC_ARCH=arch-linux2-c-debug
<<<<<<<<<<
However some older make version might not display this info properly. [it
should use the user specified '-j' value though]
This confused me, and now I understood. But it is misleading. Could we do
something at the PETSc side regardless the make version? At least display the
user-specified value not the default value. I thought my "-j" did not change
anything.
Fande,
>>>>>>>
[petsc@ipro petsc.maint ((879a78556f...))]$ make -j2
Using MAKEFLAGS: -j7 -l12.0 w --jobserver-fds=3,4 -j --
PETSC_DIR=/Users/petsc/petsc.maint PETSC_ARCH=arch-osx-10.6
<<<<<<<
You can use the alternate mode - just modify the default '-j' value used MAKE_NP
>>>>>>>>
[petsc@ipro petsc.maint ((879a78556f...))]$ make MAKE_NP=2
Using MAKEFLAGS: -j2 -l12.0 w -- PETSC_DIR=/Users/petsc/petsc.maint
PETSC_ARCH=arch-osx-10.6 MAKE_NP=2
<<<<<<<
Or you can control this default value at configure time [this affects
externalpackage builds]
./configure --with-make-np=2
Satish
On Tue, 24 Jul 2018, Fande Kong wrote:
> Thanks, Jed and Satish,
>
>
> But "make -j N" does not change anything when compiling petsc.
>
>
>
> If I do something like: "make -j whatever". Then I always get:
>
>
> Using MAKEFLAGS: -j8 -l36.0 w
>
>
> It looks like PETSc always uses "-j something" that we can not change using
> the command-line.
>
>
> Is it a bug?
>
>
>
> Fande,
>
>
>
> ________________________________
> From: Jed Brown <[email protected]>
> Sent: Tuesday, July 24, 2018 3:44 PM
> To: Fande Kong; For users of the development version of PETSc
> Subject: Re: [petsc-dev] could we let "make -j N" work for PETSc and external
> packages?
>
> Fande Kong <[email protected]> writes:
>
> > Hi Developers,
> >
> >
> > Could we somehow let "make -j N" to take multiple threads for compiling
> > PETSc. Do we use multiple threads when compiling the external packages such
> > as hypre, parmetis etc.?
>
> Yes, see self.parallelMake=0 for the few packages that don't support parallel
> make.
>
