Interrupt load with niced processes

[YONETANI Tomokazu]

On Thu, Jun 07, 2007 at 12:13:00PM +0300, Hasso Tepper wrote:
> I noticed that even if I nice my compile jobs to 20, my desktop still
> lags significantly. It might not be related, but while hunting potential
> causes I noticed strange issue with load stats:
> 
> ~:# while true; do echo "foo" > /dev/null; done
> 
> 33.1%Sys   1.2%Intr 65.7%User  0.0%Nice  0.0%Idl
> 
> ~:# while true; do nice -n 20 echo "foo" > /dev/null; done
> 
> 33.3%Sys  44.2%Intr 21.9%User  0.6%Nice  0.0%Idl
> 
> 
> Just wrong stats? I didn't notice any obvious error at first glance in
> the kern/kern_clock.c, so anyone has ideas what's going on?

Usually echo is a shell-builtin, while `nice' is an executable,
and `nice -n20 echo' might also run a non-builtin version (/bin/echo),
which makes stats look differently.

Cheers.