Thomas, Even on no-op, the difference in dependency generation could be substantial. Consider comparing '--tree=prune' between a small QT target between 2.5.0 and 2.4.1 and I think you will see that they are quite different.
V/R, William On Mon, Apr 11, 2016 at 3:59 PM, Thomas Berg <merlin...@gmail.com> wrote: > Bill, below is the output of --debug=count, it is identical with > scons-2.4.1 and scons-2.5.0. > > Since my case was about the no-op build (nothing is built), less > parallelization should not be an issue. We do have about 900 Qt Moc > generated files in our build, and I guess 1-2000 other generated > files. When moving from 2.4.1 to 2.5.0, the I can see that the moc > build steps are being re-run, nothing else. Still I find it mysterious > if just a small percentage increase in the number of dependencies can > triple the scons processing time. > > If others are not seeing these slowdowns, maybe our build is getting > hit bad due to the form of our dependency graph or something. > > Thanks, > Thomas > > > Object counts: > pre- post- pre- post- > read read build build Class > 0 3277 3277 35628 Action.CommandAction > 0 220 220 220 Action.CommandGeneratorAction > 0 894 894 894 Action.FunctionAction > 0 1670 1670 1670 Action.LazyAction > 0 9 9 35 Action.ListAction > 0 1563 1563 1563 Builder.BuilderBase > 0 220 220 220 Builder.CompositeBuilder > 0 28632 28632 28632 Builder.OverrideWarner > 0 44 44 44 Environment.Base > 0 1142 1142 1142 Environment.EnvironmentClone > 0 16 16 16 Environment.OverrideEnvironment > 0 40815 40815 42115 Executor.Executor > 0 0 0 47872 Executor.Null > 0 98922 98922 107638 Node.FS.Base > 0 5285 5285 6580 Node.FS.Dir > 0 44079 44079 51437 Node.FS.File > 0 0 0 1 Node.FS.RootDir > 0 99703 99703 108420 Node.Node > > On Mon, Apr 11, 2016 at 3:47 PM, Bill Deegan <b...@baddogconsulting.com> > wrote: > > Thomas, > > > > Can you run and post with "--debug=count"? > > > > Thanks, > > Bill > > > > On Mon, Apr 11, 2016 at 7:14 AM, Thomas Berg <merlin...@gmail.com> > wrote: > >> > >> Hi all, > >> > >> First of all, thanks for the 2.5.0 release! > >> > >> I have tested it in the build at my dayjob now, where we have a large > >> C++ application built with scons: around 7-8000 .cpp files, same > >> amount of headers, some code generation steps including Qt moc-ing. > >> Unfortunately it seems that something has happened in scons-2.5.0 that > >> slows down the no-op build quite significantly. This is the output of > >> scons --debug=time in an almost-no-op build of our source tree: > >> > >> ======================================================== > >> = 2.5.0 > >> ======================================================== > >> > >> Total build time: 933.582000 seconds > >> Total SConscript file execution time: 55.395000 seconds > >> Total SCons execution time: 858.109000 seconds > >> Total command execution time: 20.078000 seconds > >> > >> ======================================================== > >> = 2.4.1 > >> ======================================================== > >> > >> Total build time: 337.473000 seconds > >> Total SConscript file execution time: 62.303000 seconds > >> Total SCons execution time: 256.638000 seconds > >> Total command execution time: 18.532000 seconds > >> > >> ======================================================== > >> = 2.3.4 > >> ======================================================== > >> > >> Total build time: 331.774000 seconds > >> Total SConscript file execution time: 61.290000 seconds > >> Total SCons execution time: 249.606000 seconds > >> Total command execution time: 20.878000 seconds > >> > >> ------------------------------------------------------------ > >> This is with python-2.7.9 64bit on Windows 7. > >> > >> So it seems that the scons execution time has increased by a factor of > >> 3 in our build, between scons-2.4.1 and 2.5.0 :( > >> > >> For us the 5.5 minute no-op build time has already been an issue, so > >> the new 15 minute no-op build is bad news. If you have just changed a > >> single file, and need to build from the top to check that everything > >> is up to date, 15 minutes is a very long time... I'm seeing similar > >> slowdowns for our partial builds where we only execute some of our > >> SConscripts (build time going from 16 to 25 seconds for example). > >> > >> 1. Is anyone else seeing this? > >> 2. Any idea what changes that could cause something like this? I could > >> try bisecting or reverting some changes to narrow it down > >> 3. Is there anything else I can do, like posting the output of > profiling? > >> > >> I also have some other smaller hobby C++ projects that I could profile. > >> > >> Thanks for any hints, > >> Thomas Berg > >> _______________________________________________ > >> Scons-dev mailing list > >> Scons-dev@scons.org > >> https://pairlist2.pair.net/mailman/listinfo/scons-dev > > > > > > > > _______________________________________________ > > Scons-dev mailing list > > Scons-dev@scons.org > > https://pairlist2.pair.net/mailman/listinfo/scons-dev > > > _______________________________________________ > Scons-dev mailing list > Scons-dev@scons.org > https://pairlist2.pair.net/mailman/listinfo/scons-dev >
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