[GAP Forum] Mystry call to Order
am at ime.usp.br
Wed Jul 16 19:01:32 BST 2008
Alexander Hulpke wrote (on Jul 16, 2008):
> Dear Armando Mandel, Dear Forum,
Hello Aexander, hello Forum and hello Armando, whoever you are :-)
> > As you can see, Order takes up all the time. However, Complete does
> > not involve any group.
> This is a known problem in the profiling code.
Maybe it should be documented.
> The call in question is
Well, this little tip was enough (see below)!
> what is happening, however, is that there is a method installation
> for `Order' for groups (in lib/grp.gi) for which the method is simply
> the operation `Size'. This means, that the function `Size' internally
> gets labeled as a *method* for the operation `Order' for groups.
> unfortunately this is not easily fixed: doing so would require an
> extra indirection when calling methods, which are operations
> themselves. This would slow things down a little bit. In view of this,
> I would argue that the mislabeling of the profile is the lesser evil.
No problem, so long I am aware of it.
Your remarks about how profiling may be self-deceiving occasionally
notwithstanding, profiling was smack in the head this time. There
were definitely many calls to Size in the inner loops. I change that
by keeping tab myself of the sizes of the relevant lists in variables.
The effect was dramatic. Here is the timing of the two runs I
argument before after
very small 2250 20
small 1323640 1310
large forever 96710
I am not kidding - BTW, the timings in this case were little affected
by the profiling.
Thanks again for your help,
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