Re: [ECOS] ISR to DSR delay?

[Andrew Lunn <andrew at lunn dot ch>]

On Thu, Oct 13, 2005 at 03:23:57PM +0200, Stefan Sommerfeld wrote:
> Hi,
> 
> >On Thu, Oct 13, 2005 at 02:42:58PM +0200, Stefan Sommerfeld wrote:
> >>BTW: Why is "c++ empty delete function" a default option? I took me a 
> >>day
> >>to find out why my system consumes a lot memory.
> >
> >Its a philisophical thing.
> >
> >Small footprint embedded systems, which is what eCos is targeted to,
> >tend to use static allocated memory. That way they know they have
> >enough memory either at compile time, or just after the system has
> >started running when it allocates all the memory it needs for the rest
> >of its life. This also makes the code simpler and smaller. You don't
> >need to worry about running out of memory if you survive the startup
> >phase. It is not normal to free memory since objects live until the
> >system crashes/reboots. In such systems delete() is just a waste of
> >space, but the linker is unlikely to be able to throw it away. So an
> >empty implementation is used.
> 
> Of course, i agree it's an important function for embedded system, but i 
> would suggest that it's not by default enabled.
> 
> >Now i guess you are not using eCos for what its primarily targeted
> >to. If you are using C++ with dynamically allocated objects you are
> >probably on a big fat footprint embedded system.
> 
> I'm using eCos as a RTOS ... XScale 520MHz with 64MB RAM :)

So a very very fat footprint system. I expect most systems running
eCos are around 1MB-2MBs of RAM.

> >
> >What i suppose we could do to help people in your situation is that if
> >INFRA_DEBUG is enabled add a counter to count the number of times
> >delete() is called. If it exceeds 100 throw an assert. When the assert
> >goes off and you start investigating it, it will quickly become
> >obvious what you need to do....
> 
> That would be an option ....

I will add it to my ToDo list.

        Andrew

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