Hi, Vince, Thanks very much for your comments! I will check the paper.
Best Regards Nan Xiao On Wed, Mar 11, 2015 at 10:00 PM, Vince Weaver <[email protected]> wrote: > On Wed, 11 Mar 2015, Nan Xiao wrote: > >> Compared with the previous output, the numbers decrease drastically >> (For load instruction: 89,261 vs 1,779,954; store instruction: 12,002 >> vs 6,601,675). This time, I think the more load/store instructions >> (70,089,261 vs 70,000,000, 20,012,002 vs 20,000,000) are from bash >> executing the whole command(perf stat -a -e "r81d0:u","r82d0:u" >> ./a):parse the command, fork process, etc. > > perf is very careful to only count the actual process you are running, so > the overhead probably doesn't involve bash in any way. > > x86 processors have many sources of overhead/overcount. if you're really > interested in the low-level details you can read my ISPASS 2013 paper > found here: > > http://web.eece.maine.edu/~vweaver/projects/deterministic/deterministic_counters.pdf > > > Vince -- Best Regards Nan Xiao -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
