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| author | Matt Fleming <matt@codeblueprint.co.uk> | 2016-12-23 15:17:53 +0000 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-01-23 11:37:13 -0800 |
| commit | 961518259b3ba79a3cfc634794dc12ea9565dac4 (patch) | |
| tree | ce1608e8528dc2e6830d460b797fa5703ac0c04c /lib/Kconfig.debug | |
| parent | fdbb9b315ce40922f3a8d2b8352776d7bc963d84 (diff) | |
| download | lwn-961518259b3ba79a3cfc634794dc12ea9565dac4.tar.gz lwn-961518259b3ba79a3cfc634794dc12ea9565dac4.zip | |
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@techsingularity.net>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'lib/Kconfig.debug')
| -rw-r--r-- | lib/Kconfig.debug | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index b06848a104e6..5655bd95919a 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 |