Why are precompiled versions faster than those built from source code?

asked 2017-07-24 18:07:48 +0100

anonymous user

Anonymous

updated 2017-07-24 21:40:13 +0100

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 ( 2017-07-24 22:05:20 +0100 )edit

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 ( 2017-07-25 20:22:31 +0100 )edit
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