Re: [Linux-ia64] What's taking all the system time..?

[Stephane Eranian <eranian@frankl.hpl.hp.com>]

Duraid,

> 
> 	I've got a big (production) code that depends on a simple 'graph'
> library in C++. To try it out on Itanium, I stripped it down and whipped up
> a tiny 'benchmark' of the graph library. When I tried this on an Itanium
> system here (2.4.9-SMP, gcc/g++ 2.96/3.0.3 and intel c++ 6.0) the code runs
> for about 30 seconds, 20 of which is reported as 'system' time. The thing
> is, this is (supposed to be) a CPU-bound job: on my home x86 system, it runs
> in about 3 seconds, and with negligible system time.
> 
> 	'top' and 'time' show the gobs of system time being used, but
> 'strace' picks up nothing out of the ordinary (0.014 seconds system time,
> dominated by calls to brk() (this is expected).
> 
Just by curiosity, have you looked at the system log in /var/log/messages?
I am guessing your program does some floating point operations.
Have you seen something about floating-point software assist? Another 
potential cause could be unaligned accesses. That you can also see 
in the system log.

-- 
-Stephane