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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>From:</b> Satish Balay <balay@mcs.anl.gov><br>
<b>Sent:</b> Tuesday, July 24, 2018 4:06 PM<br>
<b>To:</b> Fande Kong<br>
<b>Cc:</b> Jed Brown; For users of the development version of PETSc<br>
<b>Subject:</b> Re: [petsc-dev] could we let "make -j N" work for PETSc and external packages?</font>
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<div class="BodyFragment"><font size="2"><span style="font-size:11pt;">
<div class="PlainText">PETSc configure sets up a default value that always gets used.<br>
<br>
>>>>>>><br>
balay@asterix /home/balay/tmp/petsc (maint=)<br>
$ make<br>
<snip><br>
Using MAKEFLAGS: -j4 -l6.0 w -- PETSC_DIR=/home/balay/tmp/petsc PETSC_ARCH=arch-linux2-c-debug<br>
<<<<br>
<br>
You can always override this default by adding a -j option. [since the<br>
user specified -j value comes at the end - it overrides the one that<br>
is specified at the begining of make command]<br>
<br>
>>>>>>>>>><br>
balay@asterix /home/balay/tmp/petsc (maint=)<br>
$ make -j20<br>
<snip><br>
Using MAKEFLAGS: -j4 -l6.0 w -j20 --jobserver-auth=3,4 -- PETSC_DIR=/home/balay/tmp/petsc PETSC_ARCH=arch-linux2-c-debug<br>
<<<<<<<<<<<br>
<br>
<br>
However some older make version might not display this info properly. [it should use the user specified '-j' value though]<br>
<br>
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.<br>
<br>
Fande,<br>
<br>
>>>>>>><br>
[petsc@ipro petsc.maint ((879a78556f...))]$ make -j2<br>
Using MAKEFLAGS: -j7 -l12.0 w --jobserver-fds=3,4 -j -- PETSC_DIR=/Users/petsc/petsc.maint PETSC_ARCH=arch-osx-10.6<br>
<<<<<<<<br>
<br>
You can use the alternate mode - just modify the default '-j' value used MAKE_NP <br>
<br>
>>>>>>>> <br>
[petsc@ipro petsc.maint ((879a78556f...))]$ make MAKE_NP=2<br>
Using MAKEFLAGS: -j2 -l12.0 w -- PETSC_DIR=/Users/petsc/petsc.maint PETSC_ARCH=arch-osx-10.6 MAKE_NP=2<br>
<<<<<<<<br>
<br>
Or you can control this default value at configure time [this affects externalpackage builds]<br>
<br>
./configure --with-make-np=2<br>
<br>
Satish<br>
<br>
<br>
On Tue, 24 Jul 2018, Fande Kong wrote:<br>
<br>
> Thanks, Jed and Satish,<br>
> <br>
> <br>
> But "make -j N" does not change anything when compiling petsc.<br>
> <br>
> <br>
> <br>
> If I do something like: "make -j whatever". Then I always get:<br>
> <br>
> <br>
> Using MAKEFLAGS: -j8 -l36.0 w<br>
> <br>
> <br>
> It looks like PETSc always uses "-j something" that we can not change using the command-line.<br>
> <br>
> <br>
> Is it a bug?<br>
> <br>
> <br>
> <br>
> Fande,<br>
> <br>
> <br>
> <br>
> ________________________________<br>
> From: Jed Brown <jed@jedbrown.org><br>
> Sent: Tuesday, July 24, 2018 3:44 PM<br>
> To: Fande Kong; For users of the development version of PETSc<br>
> Subject: Re: [petsc-dev] could we let "make -j N" work for PETSc and external packages?<br>
> <br>
> Fande Kong <Fande.Kong@inl.gov> writes:<br>
> <br>
> > Hi Developers,<br>
> ><br>
> ><br>
> > 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.?<br>
> <br>
> Yes, see self.parallelMake=0 for the few packages that don't support parallel make.<br>
> <br>
<br>
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