[cmake-developers] Changes for v3.5.0

[Alan W. Irwin]

On 2016-02-10 09:16-0500 Brad King wrote:

> On 02/10/2016 05:34 AM, Bartosz Kosiorek wrote:
>> I have great news.
>> With Nighly Build 3.5.20160208 the regression was gone
>
> Great, thanks for testing this!

I got curious about how this affected the timing of configuration of
the PLplot build so here are my results for that where in all cases I
am taking timing numbers from the second run of cmake (starting with
an empty build tree each time cmake is invoked) to account for all
speed gains from ccache and memory caching.  All CMake versions used
below were built by me on Linux (Debian jessie) with the bootstrap
method using export CFLAGS='-O3' export CXXFLAGS='-O3'.  So this speed
test between the various CMake versions should be a reasonably level
playing field.

Time required to configure PLplot with various versions of cmake:

3.3.2:
real    0m15.678s
user    0m11.472s
sys     0m2.432s

3.4.3:
real    0m16.351s
user    0m11.988s
sys     0m2.468s

3.5.0-rc2 (that tagged version from the git release branch this morning)
real    0m16.167s
user    0m11.812s
sys     0m2.568s

The 0.7 second increase in real time between 3.3.2 and 3.4.3 likely
indicates a small (~4 per cent) but acceptable systematic regression
in efficiency between those two versions. However, the 0.2 second
decrease in real time between 3.4.3 and 3.5.0-rc2 is likely close to
the measurement errors.  Nevertheless, that result is consistent with
Bartosz's result that the original large regression in efficiency he found
for 3.5.0-rc1 compared to prior versions has now been completely
solved for 3.5.0-rc2.

My thanks to Bartosz for finding this efficiency regression for
3.5.0-rc1, and my thanks to Brad for fixing it for 3.5.0-rc2.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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Linux-powered Science
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