Re: Re: [MLUG] Linux time command -- "kernel mode" and "user mode"

[Mike Miller <EMAIL:PROTECTED>]

On Fri, 3 Nov 2006, Jonathan King wrote:

> > Or another possibility.  The reformatting of the data in the C++ 
> > program involves a lot of calling malloc, which in turn will probably 
> > call things like mmap.  This would push a lot of the tasks from the 
> > user to the kernel.  But this would not be a bad thing in of itself, if 
> > it actually leads to slightly better performance.  (Whereas using the 
> > swap space a lot strikes me as excessively ugly.)
>
> Something does seem pretty screwy here. He says he's keeping *300* files 
> open in the Python version, while the C++ is doing things one at a time. 
> I'm thinking the only thing that's keeping Python in the ballpark is 
> that it's doing something better with caching writes and then doing all 
> of them at once. Would it be possible to post the code, or at least a 
> skeleton that shows the i/o? My guess is that as soon as they saw the 
> code, half of the C++ dudes on the list could point to some crucial 
> inefficiency you could fix.
>
> Or, maybe Python really can be pretty clever here.


I would love to have some of you guys look at the code.  It's all GPL, but 
it has a fairly obscure use -- it isn't anything you would find a need 
for.  I should also send example input data so that you could run the 
program on it, if you wanted to.  I'll try to get to it tomorrow or 
Tuesday.

Mike

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