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Re: [nslu2-linux] rrdtool performance issue

To: <nslu2-linux@xxxxxxxxxxxxxxx>
Subject: Re: [nslu2-linux] rrdtool performance issue
From: "Phil Endecott" <spam_from_nslu2_linux@xxxxxxxxxxxx>
Date: Fri, 15 Jun 2007 11:11:50 +0100
>> > I installed cacti on my nslu2 (cpu @ 266) and it takes about 10+
>>  > minutes to create a graph (just one graph..)

> I've found that rrdtool is the one causing the delay.. and actually
> after a bit of testing the GPRINT is causing it. When I don't place
> GPRINT function to get Current: Average: or Max: then I have a graph
> in 2-3 secs while by using even just one GPRINT it takes 5-6 minutes
> to create the graph.. CPU-bound..
>
> Do you know what GPRINT function in rrdtool does exactly (apart from
> the obvious printing of text on graph) ?
> It can't be that intensive just by calculating average or getting the
> max out of the data.

The Slug's processor doesn't have a floating-point unit so computing 
the average could be slow, but I wouldn't expect it to be *that* bad.

Does GPRINT use different font rendering than the other rrdtool text?  
I believe that rrdtool uses freetype for fonts.  There is probably 
quite a lot of work going on there, but again it shouldn't be *that* bad.

Try to GPRINT a constant number; that will give another clue.

Are you quite certain that it isn't swapping?

I think you'll need to look at or profile the code, or find an rrdtool 
mailing list to ask on.


Regards,

Phil.






 
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