On Mon, Aug 15, 2016 at 07:03:00AM +0200, Ingo Molnar wrote: > > * Linus Torvalds <torva...@linux-foundation.org> wrote: > > > Make sure you actually use "perf record -e cycles:pp" or something > > that uses PEBS to get real profiles using CPU performance counters. > > Btw., 'perf record -e cycles:pp' is the default now for modern versions > of perf tooling (on most x86 systems) - if you do 'perf record' it will > just use the most precise profiling mode available on that particular > CPU model. > > If unsure you can check the event that was used, via: > > triton:~> perf report --stdio 2>&1 | grep '# Samples' > # Samples: 27K of event 'cycles:pp'
Problem here is that Dave is using a KVM thingy. Getting hardware counters in a guest is somewhat tricky but doable, but PEBS does not virtualize.
