On Wed, Aug 30, 2017 at 02:20:37PM +0900, Sergey Senozhatsky wrote: > Byungchul, a quick question. Hello Sergey, > have you measured the performance impact? somehow my linux-next is Yeah, it might have performance impact inevitably. > notably slower than earlier 4.13 linux-next. (e.g. scrolling in vim > is irritatingly slow) To Ingo, I cannot decide if we have to roll back CONFIG_LOCKDEP_CROSSRELEASE dependency on CONFIG_PROVE_LOCKING in Kconfig. With them enabled, lockdep detection becomes strong but has performance impact. But, it's anyway a debug option so IMHO we don't have to take case of the performance impact. Please let me know your decision. > `time dmesg' shows some difference, but probably that's not a good > test. > > !LOCKDEP LOCKDEP LOCKDEP -CROSSRELEASE -COMPLETIONS > real 0m0.661s 0m2.290s 0m1.920s > user 0m0.010s 0m0.105s 0m0.000s > sys 0m0.636s 0m2.224s 0m1.888s > > anyone else "sees"/"can confirm" the slow down? > > > it gets back to "usual normal" when I disable CROSSRELEASE and COMPLETIONS. > > --- > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index b19c491cbc4e..cdc30ef81c5e 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1091,8 +1091,6 @@ config PROVE_LOCKING > select DEBUG_MUTEXES > select DEBUG_RT_MUTEXES if RT_MUTEXES > select DEBUG_LOCK_ALLOC > - select LOCKDEP_CROSSRELEASE > - select LOCKDEP_COMPLETIONS > select TRACE_IRQFLAGS > default n > help > > --- > > -ss
