GTA04 Block V4

joerg at joerg at
Fri May 2 05:06:58 CEST 2008

Am Fr  2. Mai 2008 schrieb Werner Almesberger:
> joerg at wrote:
> > We *can* do *instant* 'resume' with 6400, just by software improvements,
> That depends on your definition of "instant". I just measured the time
> from the falling edge of ONKEY until the call to s3c2410_pm_debug_init
> in arch/arm/plat-s3c24xx/pm.c:s3c2410_pm_enter: a bit over 50ms.
> (The printks in s3c2410_pm_do_restore_core don't make a significant
> difference.)
> This include 14ms debounce time for ONKEY, so just getting to the point
> where the kernel can do anything at all takes about 35ms. Note that this
> is just the core bringup - power, PLLs, DRAM, and a few dozen register
> settings, but no device drivers, no user space processes.

So this is a clear knockout for "ultrafast resume", by giving near 100% of 
CPU-load with as few as 10 events per second. There are cases where we might 
have to service more than 10 events per seconds and still the CPU is 

Anyway thanks for the facts, that's the kind of info we need to make sensible 
decision on MCU :-)
Now give me a usecase where we *have to* handle high amounts of events / 
second in a simple way while CPU powered down, and the killer argument pro 
MCU is born.


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