Robert Richter <robert.rich...@amd.com> wrote on 2011/11/18 00:20:27: > > On 17.11.11 22:27:46, Joakim Tjernlund wrote: > > > >> For my e300c2 cpu both if's are false and I don't get support for > > > >> callgraph/backtrace > > > >> support. Moving the ops->backtrace = op_powerpc_backtrace; to the top > > > >> enables backtrace for me. > > > It sure seems to work :) > > Backtrace support also works in timer mode. This is already > implemented on arm and sh (out of my mind, have to look at the code to > be sure). This works if the architectural initialization code sets up > ops->backtrace even on failure, which is exactly what you proposed. > > > Question, what is the sample rate for timer based oprofile? > > Is it HZ depended? > > Yes, it uses the high resolution timer and sets it to HZ which is 4ms > on most architectures. (I did some measurements and for some reason I > got 8ms on x86 though it should be 4ms, but didn't debug this yet.)
1-4 ms is a bit rough sample rate I guess. Ever considered using an extra HW timer(for CPUs that has one to spare) which can set to something better? > > Unless there are volunteers I will queue up a patch for v3.3 to enable > backtrace support in timer mode. That would be nice, thank you. Jocke _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
