Phil, On Wed, Apr 16, 2008 at 11:22 AM, Philip Mucci <[EMAIL PROTECTED]> wrote: > Folks, > > hpcrun does it's sampling inside the target process using first person > access, not a 3rd person ptrace() like pfmon, so the process is > implicitly blocked when processing samples, i.e. there are no dropped > samples unless something else has gone wrong. > Thanks for clarifing this. It makes more sense given how PAPI works.
> Another thing, you cannot rely on the sample count of hpcrun to > compute cycles. Why? Because those are samples that only have not been > dropped. If samples occur ourside of the sample space (as can happen > when one has floating point exceptions), the address will be in kernel > space and it will be dropped. pfmon has no concept of filtering out > addresses, so even if you ask for user-space samples, you'll still get > samples in the output with kernel addresses. I'm not sure what the > default is for your version of pfmon. > PFmon does not do filtering of samples. It relies on the hardware via the priv levels. By default, pfmon only measures at the user level. That does not mean you won't get kernel-level samples because there are boundary effects when sampling. > Which value is correct, according to /bin/time? 2Billion or 154 Billion? > This is a valid point. Which value makes most sense related to time? ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ perfmon2-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
