#18987: Parallel computation for TilingSolver.number_of_solutions
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Reporter: | Owner:
slabbe | Status: needs_work
Type: | Milestone: sage-6.9
enhancement | Resolution:
Priority: major | Merged in:
Component: | Reviewers: Vincent Delecroix
combinatorics | Work issues:
Keywords: | Commit:
Authors: | cbbc26242b1883f8a51065ccd7e8e97e6154025b
Sébastien Labbé | Stopgaps:
Report Upstream: N/A |
Branch: |
u/slabbe/18987 |
Dependencies: |
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Comment (by slabbe):
Replying to [comment:15 vdelecroix]:
> Replying to [comment:13 slabbe]:
> > > Why? If your parallization ends with a time better than `total_time
/ nb_cpus` then you should parallelize more often ;-)
> >
> > I have 240 subproblems each of them taking between 20 minutes and 10
hours of computation. But my machine at work only have 4 cores. So one way
or the other, the computation takes days to finish since I do not have
access to a super machine.
>
> This looks very bad. At the end, you might end up with only one core
working on the biggest subinstance. And it can lasts several days even
with 200 cores. Ideally, you should slice the problem in such way that
each subinstance will not take longer than 1 hour (let say). This is why
adopting a less naive strategy at the level of dancing links seems to me
the best option since people already worked on it.
It is not very bad as most of the 240 computations takes the same amount
of time (about 2 to 3 hours). Maybe 5 of time takes more (10 hours). So I
am using the four cores at least 95% of the time. In my case, I have very
good subinstances to reuse your term.
>
> There is no super computer in Liege?
Well maybe there is something. It is the first time in Liège that I need
computation power, but it is the vacation now.
> I can set an invitation to use the very powerful
[https://plafrim.bordeaux.inria.fr/doku.php Plafrim] in Bordeaux. But it
is some work to learn how to use it (e.g. you need to tell in advance for
how long you request the processors).
That would be nice!
--
Ticket URL: <http://trac.sagemath.org/ticket/18987#comment:18>
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