On Thu, 2012-08-16 at 14:23 +1000, Michael Neuling wrote: > > On this second syscall, fetch_bp_busy_slots() sets slots.pinned to be 1, > despite there being no breakpoint on this CPU. This is because the call > the task_bp_pinned, checks all CPUs, rather than just the current CPU. > POWER7 only has one hardware breakpoint per CPU (ie. HBP_NUM=1), so we > return ENOSPC.
I think this comes from the ptrace legacy, we register a breakpoint on all cpus because when we migrate a task it cannot fail to migrate the breakpoint. Its one of the things I hate most about the hwbp stuff as it relates to perf. Frederic knows more... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
