A couple of suggestions: 1. Check your value of TMPDIR if any. All -O is doing is redirecting output into a temp file and dumping it later. Effectively it turns command "foo" into "foo > $TMPDIR/blah; cat $TMPDIR/blah; unlink $TMPDIR/blah". This is why it seems almost impossible for it to slow things down appreciably, and a slow temp dir device might be one explanation. Along similar lines you could try "TMPDIR=/tmp make ..."
2. Try strace. It has a mode which will timestamp each system call and another which prints a table of system calls used and how much time it took. One of these will probably be instructive, especially when compared with the same without -O. David On Sun, Jul 17, 2016 at 12:22 PM, Gardell, Steven <sgard...@sonusnet.com> wrote: > No I have not gotten to 4.2.1 yet. > > I have experimented using j values ranging from 16 to 64. The majority of > the testing is with -Otarget. But I have tried all of them. > > -----Original Message----- > From: Paul Smith [mailto:psm...@gnu.org] > Sent: Sunday, July 17, 2016 3:14 PM > To: Gardell, Steven <sgard...@sonusnet.com>; Bug-make@gnu.org > Subject: Re: Parallel builds across makefiles > > On Sun, 2016-07-17 at 15:48 +0000, Gardell, Steven wrote: > > OK. Thanks! I will try the latest version. > > > > FWIW, I am measuring is total wall clock time to complete the build. > > (date; gmake... ; date) This goes up substantially with all sync modes > > other than "none" if gmake has parallel invocations of sub-makes going > > (e.g. "gmake -f SomeOtherMakefile"). When I am only parallelizing > > individual makefiles (with ACE, these tend to be simple lists of files > > to compile), then the behavior is as promised by the documentation. > > Assuming you determine the behavior exists even in version 4.2.1, please > provide more details. What level of -j are you using? Which sync mode are > you using? Do you get the same behavior even with lower levels of -j, if > yours is very large? > > _______________________________________________ > Bug-make mailing list > Bug-make@gnu.org > https://lists.gnu.org/mailman/listinfo/bug-make >
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