On Fri, Sep 10, 2021 at 11:33:52AM -0700, Song Liu wrote: > + /* Given we stop LBR in software, we will waste a few entries. > + * But we should try to waste as few as possible entries. We are at > + * about 7 on x86_64 systems. > + * Add a check for < 10 so that we get heads-up when something > + * changes and wastes too many entries. > + */ > + ASSERT_LT(skel->bss->wasted_entries, 10, "check_wasted_entries"); It might be worth pointing out that you can easily bust this limit by enabling all the various tracepoints that are still in that code, but that that isn't a hard error since that's not the expected use case. For example there's the wrmsr tracepoint that will inject 6 or so branches on top of that you now have. And I also think there's a tracepoint in local_irq_save() that can trigger.
