#11900: Serious regression caused by #9138
---------------------------+------------------------------------------------
Reporter: SimonKing | Owner: tbd
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.7.3
Component: performance | Keywords: categories regression
Work_issues: | Upstream: N/A
Reviewer: | Author: Simon King
Merged: | Dependencies: #9138 #11911
---------------------------+------------------------------------------------
Changes (by SimonKing):
* status: needs_work => needs_review
* work_issues: fix doctests =>
Old description:
> 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.
New description:
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.
Apply:
* [attachment:trac11900_no_categories_for_matrices.patch]
* [attachment:trac11900_category_speedup.patch]
--
Comment:
I think "new coercion model for libsingular" does not really fit to this
ticket. Hence, I am not doing it in my new patch anymore.
It fixes many slownesses of the category framework that became unbearable
with #9138. I am convinced that further tweaks are possible. For example,
base ring independence of parent and element classes would have a
significant impact on efficiency. But again, I believe that that should be
on a different ticket.
All doc tests pass and thus it is "needs review". I'm now trying to
collect some evidence supporting my patches.
Apply trac11900_no_categories_for_matrices.patch
trac11900_category_speedup.patch
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11900#comment:63>
Sage <http://www.sagemath.org>
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