Re: [Gumstix-users] reliable setitimer?

[Jim W. <jwa...@qu...>]

Hi Brad,

I've just been adding timers to some of my code this week, so I don't 
have a lot of experience to add, but I'll let you know what's working 
for me.

First of all, I did most of my prototyping on a desktop, and only moved 
the final chunk of code to the gumstix after it seemed to be working 
good on the PC.  I started using setitimer based code, but I found that 
creating multiple concurrent timers seemed complex.  From what I can 
tell (I read part of a book, Unix Systems Programming - communication, 
concurrency, and threads by Kay and Steven Robbins, and got most of my 
information from there) the setitimer function and related routines are 
part of the POSIX:XSI extension.  There is another group of timer 
routines that use timer_create, timer_gettime, and timer_settime that 
are part of the POSIX:TMR extension. I did find some additional ease of 
use in creating multiple timers and handling the signals from the timers 
with the POSIX:TMR routines, so that is what I ended up using.  The 
timers that I am using are in the half second to multiple second range, 
so they aren't going to be testing the same kinds of timing and 
performance situation that you are looking for, but they are working 
fine for me on the gumstix (for a whole day now!)

Thanks,

Jim Walters

Craig Hughes wrote:

> dunno -- try asking on the arm kernel list
>
> C
>
> On May 9, 2005, at 8:43 PM, Brad Midgley wrote:
>
>> Hi
>>
>> Going from hardcoded usleep() calls to a regularly-paced sigalrm  via 
>> setitimer vastly improved timing for stereo bluetooth audio  
>> transmission on the desktop.
>>
>> However, on gumstix it totally went south. It used to at least belt  
>> out bits and pieces of the music when it had usleep() mixed in to  
>> try to get the timing right, but with setitimer, it goes for a bit  
>> and then stops working altogether. Usually trying again produces  
>> nothing until the board is rebooted.
>>
>> I noticed a mention of a problem with setitimer fixed recently in  
>> uclinux. Related? http://blackfin.uclinux.org/tracker/index.php? 
>> func=detail&aid=609&group_id=17&atid=141
>>
>> Brad
>>
>>
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