Commit-ID: 961518259b3ba79a3cfc634794dc12ea9565dac4 Gitweb: http://git.kernel.org/tip/961518259b3ba79a3cfc634794dc12ea9565dac4 Author: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> AuthorDate: Fri, 23 Dec 2016 15:17:53 +0000 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Mon, 23 Jan 2017 11:37:13 -0800 rcu: Enable RCU tracepoints by default to aid in debugging 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@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> --- lib/Kconfig.debug | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index b06848a..5655bd9 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1450,6 +1450,7 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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