Re: [Gems-users] How to break down cycles

["Min Xu (Hsu)" <xu@xxxxxxxxxxx>]

On Thu, 03 Mar 2005 Luke Yen wrote :
>   Idle cycles can be calculated by storing some info when the front-end
> stalls and resumes fetch, if that is what you meant by idle cycles.

If you otherwise meant idle cycles in Solaris kernel, you can, at least
in theory, get the information by recognize the kernel idle loop.

The trick about kernel idle loop is that it is not "idle" from a hardware
perspective: even the idle loop is constantly looking for jobs
to execute, which by itself is doing something useful.

My recommendation to recognizing kernel idle loop is to match the kernel
PCs. You can get the kernel function that contains the idle loop from
solaris 9 source code (you are lucky if you have it :).  In the simulated
system, you should be able to use "mdb -k" to query the kernel symbols via
the function name to get the PCs you wanted. You may have to read
a lot of SPARC assembly codes too.