Messages in this thread Patch in this message | | | Date | Fri, 23 Dec 2016 09:16:25 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH] rcu: Enable RCU tracepoints by default to aid in debugging |
| |
On Fri, Dec 23, 2016 at 03:17:53PM +0000, Matt Fleming wrote: > While debugging a performance issue I needed to understand why > RCU sofitrqs were firing so frequently. > > Unfortunately, the RCU callback tracepoints are hidden behind > CONFIG_RCU_TRACE which defaults to off in the upstream kernel and is > likely to also be disabled in enterprise distribution configs. > > Enable it by default for CONFIG_TREE_RCU. However, we must keep it > disabled for tiny RCU, because it would otherwise pull in a large > amount of code that would make tiny RCU less than tiny. > > I ran some file system metadata intensive workloads (git checkout, > FS-Mark) on a variety of machines with this patch and saw no > detectable change in performance. > > Cc: Mel Gorman <mgorman@techsingularity.net> > Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Queued for testing and review, thank you!
Thanx, Paul
> --- > lib/Kconfig.debug | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index a6c8db1d62f6..7fe1ff001792 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1431,6 +1431,7 @@ config RCU_CPU_STALL_TIMEOUT > config RCU_TRACE > bool "Enable tracing for RCU" > depends on DEBUG_KERNEL > + default y if TREE_RCU > select TRACE_CLOCK > help > This option provides tracing in RCU which presents stats > -- > 2.10.0 >
| |