On Wed, 30 Mar 2005, Grant Stockly wrote:
> A routine that prints a small printk message and exits gets 100-150
> interrupts per second which causes user space programs to halt. I'm not
> sure if the interrupts would be faster without the printk statemets. I'd
> hope not, since this is a 200MHz processor we're talking about. ;)
Can we do a sanity check here.
The cpu is already doing 100 timer interupts/sec non stop, and running the
process scheduler each time, and this takes very very very little time -
if it didn't we wouldn't be running linux on the board becuase there'd be
no time left for user apps. Printk will be writing chars over /dev/ttyAM0
(the kernel console device) and from an interrupt routine!!! I bet system
clock went belly up too!
Though I've not tested it, I'm sure a very simple IRQ service routine just
incrementing counters etc, which are accessible from some /proc entry or
similar will place negligable load on the CPU and board for upto several
hundred irqs/sec.
Jim
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