On Nov 7, 5:08 pm, "William Stein" <[EMAIL PROTECTED]> wrote:
> On Nov 7, 2007 4:34 AM, John Cremona <[EMAIL PROTECTED]> wrote:
>
> > It is true that the cpu time does not include any of the child
> > processes, and also that in many cases most of the computation is done
> > by those.
>
> > In this case the cardinality is either computed via a call to the
> > libpari function ellap, or by running gp and calling the sea
> > implementation there. The crossover is at 10^18 (as you can see by
> > typing E.cardinality??) so your example is using sea via gp.
>
> > Many people agree with you that it would be more useful to have the
> > aggregate time.
>
> So do I. If anybody figures out how to compute this aggregate time in a way
> that doesn't itself significantly impact the performance of Sage, I'd love to
> add this feature to the output of "time". So far, nobody has figured out how
> to do this and explained it to any of us. Here "this" is basically
> "figuring out
> the total CPU time used by a group of unix processes."
>
Hello,
Some info on this:
sage: time?
Type: Magic function
Base Class: <type 'instancemethod'>
String Form: <bound method InteractiveShell.magic_time of
<IPython.iplib.InteractiveShell object at 0x2afc0e987550>>
Namespace: IPython internal
File: /home/was/s/local/lib/python2.5/site-packages/IPython/
Magic.py
Definition: time(self, parameter_s='')
Docstring:
Time execution of a Python statement or expression.
The CPU and wall clock times are printed, and the value of
the
expression (if any) is returned. Note that under Win32,
system time
is always reported as 0, since it can not be measured.
This function provides very basic timing functionality.
In Python
2.3, the timeit module offers more control and
sophistication, so this
could be rewritten to use it (patches welcome).
but man getrusage tells us:
getrusage() returns current resource usages, for a who of
either RUSAGE_SELF or RUSAGE_CHILDREN. The
former asks for resources used by the current process, the
latter for resources used by those of its
children that have terminated and have been waited for.
So I assume that we can either use "timeit" or patch getrusage in
python to add up the resources used by the children on top of self. I
didn't actually look at the code, so this is shooting from the hip :)
> William
Cheers,
Michael
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