SOLVED : Re: Understanding multi-core CPU usage

[dsr-mzpnVDyJpH4k7aNtvndDlA at public.gmane.org (Dan Ritter)]

On Wed, May 05, 2010 at 12:54:19PM -0400, theBlueSage wrote:
> On Tue, 2010-05-04 at 14:22 -0400, Dan Ritter wrote:
> 
> > On Tue, May 04, 2010 at 02:12:36PM -0400, theBlueSage wrote:
> > > Hi Folks,
> > > 
> > > summary of aaagh!
> > > --------------------
> > > I was wondering if there is a tool out there that can tell me, on a
> > > 64bit multi-core server, which exact process is hammering a given CPU
> > > core ?
> > 
> > top with option field j shows last processor associated.
> > 
> > -dsr-
> > 
> 
> 
> Thanks Dan, but I cant seem to add the option 'j', neither as an
> addition to the command line, nor as a key in interactive mode while top
> is running :( However, realizing that it _must_ be possible, from your
> response, I went on a little journey and came up with these lovely
> little tools and thought I should post back in case anyone else runs
> into this issue

man top
2. Fields / Columns
 2a descriptions

               Listed below are top???s available fields.  They are
always associated with the letter shown, regardless of the position
you may have estab??? lished for them with the ???o??? (Order fields)
interactive command.

       Any field is selectable as the sort field, and you control
whether they are sorted high-to-low or low-to-high.  For additional
information on sort provisions see topic 3c. TASK Area Commands.

...

       j: P  --  Last used CPU (SMP)

          A number representing the last used processor.  In a true SMP
envi??? ronment this will likely change frequently since the kernel
intentionally uses weak affinity.  Also, the very act of running top may
break this weak affinity and cause more processes to change CPUs more
often (because of the extra demand for cpu time).

....

Glad to see you got it elsewhere, though -- I wouldn't have
thought of mpstat, myself.

-dsr-