Mail Archives: cygwin/2003/08/27/20:16:37
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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