Interrupt performance

[Slawa Olhovchenkov]

On Fri, Jan 28, 2011 at 07:44:57PM +0200, Stefan Lambrev wrote:

> >> there are profiling tools that you may decide to run.
> > 
> > What tools I can use on amd64?
> 
> Look at this document - http://software.intel.com/sites/oss/pdfs/profiling_debugging_freebsd_kernel_321772.pdf
> It contains brief information for all useful profiling tools, or just google for "freebsd kernel profiling"
> I'm not sure what the situation with RealTek driver, but in the past when I have done profiling, I saw that much of
> the CPU time was spent on expensive (for FreeBSD) calls, which where very cheap in linux.

kgmon badly work on amd64.
PmcStat don't supported on this CPU.

Also,
http://lists.freebsd.org/pipermail/freebsd-questions/2008-October/183977.html

===
This is one of many defects that are not present in high resolution
kernel profiling (kgmon -B instead of kgmon -b; availaible on amd64
and i386).  However, high resolution kernel profiling doesn't work
right with SMP, and was completely broken by gcc-4.  Ordinary
profiling
was less completely broken by gcc-4, and you can recover the old
behaviour by turning off new optimizations (mainly -funit-at-a-time
and/or -finline-functions-called-once and or all of -O2).
===

> > 
> > I boot kernel configured with 'config -p'.
> > Most time in spinlock_exit and acpi_cpu_c1.