#11900: Serious regression caused by #9138
---------------------------+------------------------------------------------
Reporter: SimonKing | Owner: tbd
Type: defect | Status: new
Priority: critical | Milestone: sage-4.7.2
Component: performance | Keywords: categories regression
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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At [http://groups.google.com/group/sage-
devel/browse_thread/thread/d885434ba9c22d66 sage-devel], Jeroen reported a
massive regression in elliptic curve computations. The regression was
introduced in the transition from sage-4.7.2.alpha2 to sage-4.7.2.alpha3.
It seems that #9138 is responsible, at least for a big part of the
regression. With unpatched sage-4.7.2.alpha2, we find
{{{
sage: E = J0(46).endomorphism_ring()
sage: %time g = E.gens()
CPU times: user 5.54 s, sys: 0.15 s, total: 5.69 s
Wall time: 5.81 s
}}}
Adding #9138 and its dependency, we obtain
{{{
sage: E = J0(46).endomorphism_ring()
sage: %time g = E.gens()
CPU times: user 8.72 s, sys: 0.18 s, total: 8.89 s
Wall time: 8.92 s
}}}
It turns out that much time is wasted for calls to
`sage.categories.Category.join` and to
`sage.categories.Category.hom_category`.
When caching these two methods, one can reduce the speed difference to
something like that (sage-4.7.2.alpha3 plus #11115 plus an experimental
patch for the caching):
{{{
sage: E = J0(46).endomorphism_ring()
sage: %time g = E.gens()
CPU times: user 6.82 s, sys: 0.16 s, total: 6.98 s
Wall time: 7.40 s
}}}
However, that's still far from good. After caching join and hom_category,
there is still too much time spent (according to %prun) for the
initialisation of matrix spaces.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11900>
Sage <http://www.sagemath.org>
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