On Sun, Feb 28, 2016 at 04:31:49PM +0000, Liang, Kan wrote:
> > static void account_pmu_sb_event(struct perf_event *event) {
> > if (event->parent)
> > return;
> >
> > if (event->attach & ATTACH_TASK)
> > return;
^^^^ this
> > if (event->attr.mmap || event->attr.mmap_data || event->attr.mmap2)
> > attach_sb_event(event, sb_mmap);
> >
> > if (event->attr.comm || event->attr.comm_exec)
> > attach_sb_event(event, sb_comm);
> >
> > if (event->attr.task)
> > attach_sb_event(event, sb_task);
> >
> > if (event->attr.context_switch)
> > attach_sb_event(event, sb_switch);
> > }
> > And then you can replace the whole global part of perf_event_aux (which I
> > would rename to perf_event_sb), with this.
> >
> > You still have to do something like:
> >
> > for_each_task_context_nr(ctxn) {
> > ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
> > if (!ctx)
> > continue;
> > perf_event_sb_ctx(ctx, output, data);
> > }
> >
>
> I'm not sure why we need something like for_each_task_context_nr(ctxn) in
> perf_event_aux/perf_event_sb.
> Isn't perf_event_sb_mask enough?
> It looks perf_event_sb_mask will go through all possible interested events
> (includes both per cpu and per task events).
See sites marked "^^^ this"
This stuff explicitly does not handle task events, because of the below:
> > To get at the per task events, because I don't think we want to go update
> > more global state on context switch, nor am I entirely sure its worth it to
> > keep per sb ctx->event_list[]s.
^^^ this
