Why are precompiled versions faster than those built from source code?
 
  
 
 
     
 
 
 
 
 
 
 
    
        
        asked 7 years ago  
 anonymous user 
Anonymous
 
 
 
 
    
        
        updated 7 years ago  
 
 vdelecroix gravatar image  
 
 
 
 
 
Maybe I am missing an environment variable or make target but my builds
are always slower.
 
For example
 
%time _ = bernoulli(3*10^5)
 
finishes in about 2 min. 30 sec. using a precompiled
version but 31 min. 41 sec. built from source (7.6) and 47 min. from source (8.0) and
 
time a = N(pi, digits=5000000)
 
finishes in 13 min. 42 sec. from source (7.6) and 20 min. 21 sec. from source (8.0)
 
I use SAGE64=yes and SAGE_INSTALL_GCC=no
Is it PARI/GP tuning or MPIR vs. GMP or some other thread related problem?
 
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Comments
Have you checked the build logs for errors and other anomalies? 
grep -ls "^Error" logs/pkgs/*
Richard_L gravatar imageRichard_L (
    
        7 years ago
    )
For what it's worth, runtimes on my laptop (Core i5-6300U, 2.4 GHz) are:  
sage: version()
'SageMath version 7.6, Release Date: 2017-03-25'
sage: %time
sage: b=bernoulli(3*10^5)
CPU time: 41.59 s,  Wall time: 41.60 s
sage: %time
sage: a = N(pi, digits=5000000)
CPU time: 20.41 s,  Wall time: 20.42 s
and
sage: version()
'SageMath version 8.0, Release Date: 2017-07-21'
sage: %time
sage: b=bernoulli(3*10^5)
CPU time: 21.14 s,  Wall time: 21.15 s
sage: %time
sage: a = N(pi, digits=5000000)
CPU time: 10.84 s,  Wall time: 10.85 s
Both versions were built from source using gcc 5.3.1.
Richard_L gravatar imageRichard_L (
    
        7 years ago
    )
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