[PD] [PD-dev] tcl/tk 8.5, antialising, and large fonts lead to huge cpu overhead bug?

Hans-Christoph Steiner hans at eds.org
Wed Feb 21 04:57:32 CET 2007

You're right, it definitely shouldn't be that bad.  Have you tried  
this same test on different platforms, or with different versions of  
Tcl/Tk?  (I am guessing you are on Windows, which I don't use).  I  
just tried on my G4 800 with Tcl/Tk 8.4.15-cvs.  I get about 50%  
usage from one num2 at 24 point at 100hz.


On Feb 20, 2007, at 8:49 AM, Ivica Ico Bukvic wrote:

> You are absolutely right from a pragmatic perspective. However,  
> having 100
> refreshes top off a relatively recent CPU is quite worrisome and  
> IMHO should
> not be dismissed lightly as it could manifest in other contexts as  
> well.
> FWIW I did a program which had a similar feature in Qt over four  
> years ago
> (with 100Hz refreshes for several concurrent timers) and its CPU  
> usage was
> always less than 3% at that time. This either suggests that Tcl/Tk  
> is a
> total hog or that there is a bug in a code somewhere (or both).
> Hence me bringing this up...
> Ico
>> -----Original Message-----
>> From: Hans-Christoph Steiner [mailto:hans at eds.org]
>> Sent: Monday, February 19, 2007 10:22 PM
>> To: ico at vt.edu
>> Cc: pd-dev at iem.at
>> Subject: Re: [PD-dev] tcl/tk 8.5, antialising, and large fonts  
>> lead to
>> huge cpu overhead bug?
>> Sounds like you are charting new territory.  I haven't worked with
>> Tcl/Tk 8.5 yet, but I think a couple people on the list have.
>> I don't know of any reason to update a GUI object more than 100 Hz
>> since that's about the max for screen refreshes.  10 Hz is probably
>> faster than we can perceive numbers anyway.
>> .hc
>> On Feb 18, 2007, at 11:03 PM, ico at vt.edu wrote:
>>> All right, unlike my previous e-mail this is perhaps not a bug, but
>>> an oddity.
>>> Nonetheless, it would be nice to know at least where it is stemming
>>> from so
>>> that I can contribute code in the right place...
>>> I've encountered unusual spike in cpu use when using antialiased
>>> tcl/tk 8.5
>>> (IIRC it also affects other antialiasing-enabled tcl/tk releases) in
>>> conjunction with large fonts. I for instance use this for my
>>> performers so that
>>> they can clearly read info even when positioned at some distance
>>> from the
>>> display monitor/LCD.
>>> One quick example would be to use a large font counter which counts
>>> 1/100ths of
>>> a second using metro and displaying it in a number2 object. This
>>> results in a
>>> 80+% (!) CPU utilization on an Athlon 64 3000+. Lowering metro to
>>> 1/10th of
>>> second drops CPU use below 5%. Similarly making font smaller does
>>> the same.
>>> Font size used is in this case is just about anything above 72.
>>> Any ideas how to circumvent this problem? Is this due to  
>>> antialiasing
>>> inefficiency in tcl/tk or some other reason? If I can be pointed in
>>> the right
>>> direction, I'll gladly provide patches...
>>> Best wishes,
>>> Ivica Ico Bukvic, D.M.A.
>>> Composition, Music Technology, CCTAD, CHCI
>>> Virginia Tech
>>> Department of Music
>>> Blacksburg, VA 24061-240
>>> (540) 231-1137
>>> (540) 231-5034 (fax)
>>> ico.bukvic.net
>>> _______________________________________________
>>> PD-dev mailing list
>>> PD-dev at iem.at
>>> http://lists.puredata.info/listinfo/pd-dev
>> --------------------------------------------------------------------- 
>> ---
>> If you are not part of the solution, you are part of the problem.


Looking at things from a more basic level, you can come up with a  
more direct solution... It may sound small in theory, but it in  
practice, it can change entire economies.     - Amy Smith

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