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Re: parallel make


First off, if you're willing to forgo the ability to access UNC paths from
Cygwin, you can set your Cygdrive prefix to '//' to address the drives in
the same way you did in your old GNU toolset (see

Secondly, why not use Cygwin perl?  This way you automatically get
the cygdrive prefix that Cygwin is configured with.

On Wed, 27 Aug 2003, Rich Elberger wrote:

> This is starting to sound promising.  I hope others have similar
> experiences.
> Unfortunately I cannot just take make and the cyg dll.  The problem comes
> in with how different utils interpret drive paths:
> our old gnu:  //c/...
> perl: c:/...
> cyg:  /cygdrive/c/... (we mount NFS exports, hence the drive notation)...
> So, we basically need to move things from the inside out rather than start
> patching things on the outside of the system, eventually getting to the
> core.  This makes the migration pretty expensive, so I would like to see
> more cases before making the resource justification case.  If it's a set
> of production machines, no problem, but the change would have to occur on
> all development workstations.
> I highly appreciate everyone's help because I think this is the only forum
> I could ever get such kind of feedback.
> -- rich
> On Wed, 27 Aug 2003, Rolf Campbell wrote:
> > make -j does work in cygwin, to an extent.  If you try to use too many
> > processes, cygwin seems to flip out.  -j20 does seem to work fine though
> > (it only starts acting strang around -j100).
> >
> > On my large build system, we have a slow disk, and I find that when the
> > disk cache is empty, -j4 speeds it up about 40%.  When the build system
> > is cached, -j slows things down by a few percent.  This is dealing with
> > 1 processor.  Of course, if you have multiple processors, the speed
> > should scale linearly (with 4 cpu's, -j4 is about 70% faster).
> >
> > Rich Elberger wrote:
> >
> > > Hi folks,
> > > Currently our build environment uses parallel make (-j jobs option) on all
> > > our unixes using gnu tools.  We use an older version of gnu tools on our
> > > windows boxes.  The older make on the windows box does not do parallel
> > > make (or at least correctly).  I want to upgrade to the latest cygwin to
> > > see if parallel make works, but this will require significant changes to
> > > our build engine, so I would like to confirm a few things if possible.
> > >
> > > 1. Does the -j jobs option work well on windows. (part b: does it work
> > > with the MSVC (6/7) compiler (which probably doesn't make a difference
> > > anyway)?
> > > 2. Has anyone done this in a very large project, and if so, do you have
> > > any performance gain stats (which, I acknowledge, is tied to
> > > processor-intensive makes and how many processors the machine has).
> > >
> > > I realize that dos does not allow for threading so I don't know if this is
> > > a cmd.exe-related issue or not (since cmd.exe is the parent shell, I
> > > don't know if this affects the behavior).
> > >
> > > thanks in advance --

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