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Groups > comp.os.linux.development.apps > #841

Re: g++ spent lots of user time

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On Wednesday, March 1, 2017 at 10:50:14 PM UTC+8, Lew Pitcher wrote:
> On Wednesday March 1 2017 09:05, in comp.os.linux.development.apps, 
> "wij@totalbb.net.tw" <wij@totalbb.net.tw> wrote:
> 
> [Text order altered]
> 
> > -----------------
> > $g++ --version
> > g++ (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1)
> > ...
> > 
> > $time g++ -c -Wall -pthread -fPIC dsmain.cpp
> > 
> > real	6m10.623s
> > user	6m8.142s
> > sys	0m0.099s
> 
> > Why did the compilation took so long in user time?
> 
> You have not provided enough information to allow anyone to give you a 
> comprehensive answer to your question.
> 
> I can give you a generic answer to your question, though.
> 
> Your compilation tool a long time because the compiler was doing lots of 
> complicated things that didn't require any system calls.
> 
> Process time is split into "the length of time the process waited while the OS 
> serviced a process-initiated system call, such as open() or read()" and "the 
> rest of the time that the process took to execute". Your "system call time" 
> (or "sys") is 0 minutes, 0.099 seconds, while your "everything else time" (or  
> "user") is 6 minutes, 8.142 seconds. That's all we can tell from the 
> information you supplied.
>  
> -- 
> Lew Pitcher
> "In Skills, We Trust"
> PGP public key available upon request

The lack of information is intentional, because it has never occurred at least
4 month before for more than 10 years, it might involve template things though.
But it contains about 1500 lines, it is not shown.
Currently, almost every object files in the Makefile takes nearly 10 more
minutes to compile. So I think it should be mostly the 'feature' of newer g++

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g++ spent lots of user time wij@totalbb.net.tw - 2017-03-01 06:05 -0800
  Re: g++ spent lots of user time Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-03-01 09:50 -0500
    Re: g++ spent lots of user time wij@totalbb.net.tw - 2017-03-01 17:12 -0800
      Re: g++ spent lots of user time Rainer Weikusat <rweikusat@talktalk.net> - 2017-03-02 15:33 +0000
  Re: g++ spent lots of user time Johann Klammer <klammerj@NOSPAM.a1.net> - 2017-03-01 17:18 +0100
    Re: g++ spent lots of user time wij@totalbb.net.tw - 2017-03-01 17:29 -0800

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