Alan W. Irwin wrote:
Hi Bill:
Plplot now builds for the cvs version of CMake so I am finally in a
position
to continue this thread.
Here is the 2.4.8 latency for the current version of PLplot
[EMAIL PROTECTED]> time make >& /dev/null
real 0m1.454s
user 0m0.800s
sys 0m0.724s
By repeating this command, I get variations of typically 0.01 seconds in
this
result. (I also confirmed the command did not actually build anything new,
i.e. it is a true measure of Makefile latency.)
For cmake version 2.7-20080320 (that cvs update done after the above
commit)
the latency has been increased (by 60 per cent) to
real 0m2.319s
user 0m1.356s
sys 0m1.068s
Again, I confirmed it was a true measure of the Makefile latency.
I also did some tests with the -r option for GNU make.
For 2.4.8 the latency is reduced by a factor of 1.5 to
[EMAIL PROTECTED]> time make -r >& /dev/null
real 0m0.970s
user 0m0.636s
sys 0m0.568s
That would indicate there is a lot to be gained by the .PHONY target for
the non-file rules in generated GNU Makefiles.
For the cvs version of CMake the latency is reduced hardly at all by
the -r option
[EMAIL PROTECTED]> time make -r >& /dev/null
real 0m2.287s
user 0m1.324s
sys 0m0.964s
In sum, the current result for the cvs version of cmake seems to create
builds with significantly increased latency compared to 2.4.8. The -r
option greatly increases this disparity. I think this is an important
enough result that further tests of "make" latency for other software
projects are important to confirm these results.
Question for Alex Nuendorf:
Alex, I imagine the KDE latency is much larger than PLplot's since your
build has _a lot_ more dependencies to check. Are the current KDE
builds in
good enough shape so that repeat make commands measure true Makefile
latency
rather than some issue with unneeded compilation, linking, or whatever? If
so, I would be very interested in your latency results for cmake-2.4.8
versus the cvs version of CMake.
Something is odd here. I don't think that much changed in the structure
of the makefiles from 2.4.8 to CVS. Did you build your CVS CMake
release or debug? What if you do make -d, is it actually checking lots
of extra stuff? Can you compare make -d in CVS and 2.4.8?
-Bill
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