On Fri, 2014-08-22 at 09:45 -0700, Dave Hansen wrote: > On 08/22/2014 09:32 AM, Tim Chen wrote: > >> > +#ifdef CONFIG_DEBUG_OBJECTS_FREE > >> > + "DEBUG_OBJECTS_FREE", > >> > +#endif > >> > +#ifdef CONFIG_DEBUG_KMEMLEAK > >> > + "DEBUG_KMEMLEAK", > >> > +#endif > >> > +#ifdef CONFIG_DEBUG_PAGEALLOC > >> > + "DEBUG_PAGEALLOC", > > I think coverage profiling also impact performance. > > So I sould also put CONFIG_GCOV_KERNEL in the list. > > Would CONFIG_GCOV_PROFILE_ALL be the better one to check? With plain > GCOV_KERNEL, I don't think we will, by default, put the coverage > information in any files and slow them down.
CONFIG_GCOV_PROFILE_ALL is definitely a no no regarding to performance impact, which is mentioned in the gcov documentation. I haven't tested this, but if profiling is turned on only for a piece of code that is performance critical but not for the whole kernel, in theory performance can still be impacted with the overhead. So I think it is safer to check for CONFIG_GCOV_KERNEL, that has no reason to be turned on for any workload that's performance critical. Tim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
