计算makefile的构建时间

Question

Any creative idea how to use enviroment variables to calculate full build time of a makefile? Can I store the time somewhere and compare it in the end?

Answer 1

I know the OP meant Windows OS, but for the record, on any Linux machine you can use time :

>time make -j
real     0m9.774s
user     0m31.562s
sys      0m1.092s

Answer 2

On Windows 7 you've got PowerShell. So we'll assume:

• Your makefile Makefile is in directory C:\\Dev\\ProjDir
• Your make tool is mingw32-make and is in your PATH

If PowerShell isn't your usual console then do:

C:\Dev\ProjDir>powershell

At the PowerShell prompt, run:

PS C:\Dev\ProjDir> Measure-Command { mingw32-make | Out-Default }

This will run your build and display the output, followed by a timing report, eg

Days              : 0
Hours             : 0
Minutes           : 0
Seconds           : 0
Milliseconds      : 244
Ticks             : 2443841
TotalDays         : 2.82851967592593E-06
TotalHours        : 6.78844722222222E-05
TotalMinutes      : 0.00407306833333333
TotalSeconds      : 0.2443841
TotalMilliseconds : 244.3841

Continued for OP's follow-up:

I was wondering if it is possible to be implemented as part of the makefile, so I can decide which part to measure

The idea of timing "part of a makefile" does not make clear sense. When you run make , it parses the entire makefile before it makes anything and works out the entire sequence of steps it must take to make the specified or default target(s). Then, it takes all those steps.

Perhaps you want to measure the time taken to make a particular set of targets? You can do that in the way already described. For example, suppose that your makefile can make two libraries libfoo.lib and libbar.lib and you would like to time the build of just libfoo.lib . To make libfoo.lib by itself, the make command you would run is:

mingw32-make libfoo.lib

So to time this command, run:

PS C:\Dev\ProjDir> Measure-Command { mingw32-make libfoo.lib | Out-Default }

Or suppose that your makefile makes app.exe from source files foo.c and bar.c , and you would like to time just the build of the object files foo.obj , bar.obj . The make command you would run to build just those object files is:

mingw32-make foo.obj bar.obj

So you would time it with:

PS C:\Dev\ProjDir> Measure-Command { mingw32-make foo.obj bar.obj | Out-Default }

Perhaps you would like to be able to invoke powershell's Measure-Command inside your makefile to time the building of particular targets?

For this, you need a command that invokes PowerShell to run some other command. That is:

powershell -c "some other command"

So in your makefile you can add a target for timing the build of any other targets:

.phony: time
time:
    powershell -c "Measure-Command { $(MAKE) $(targets) | Out-Default }"

You would use the time target like so:

C:\Dev\ProjDir>mingw32-make time targets=app.exe

or:

C:\Dev\ProjDir>mingw32-make time targets="foo.obj bar.obj"

And of course, in your makefile, the commands to build a particular target can include powershell -c "some other command" wherever you like.