From: Josh Triplett <josh@joshtriplett.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, Valdis.Kletnieks@vt.edu,
dhowells@redhat.com, edumazet@google.com, darren@dvhart.com,
fweisbec@gmail.com, sbw@mit.edu,
"Paul E. McKenney" <paul.mckenney@linaro.org>
Subject: Re: [PATCH tip/core/rcu 1/2] rcu: Provide RCU CPU stall warnings for tiny RCU
Date: Sun, 27 Jan 2013 21:57:08 +1100 [thread overview]
Message-ID: <20130127105708.GD3119@leaf> (raw)
In-Reply-To: <1359246227-5770-1-git-send-email-paulmck@linux.vnet.ibm.com>
On Sat, Jan 26, 2013 at 04:23:46PM -0800, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paul.mckenney@linaro.org>
>
> Tiny RCU has historically omitted RCU CPU stall warnings in order to
> reduce memory requirements, however, lack of these warnings caused
> Thomas Gleixner some debugging pain recently. Therefore, this commit
> adds RCU CPU stall warnings to tiny RCU if RCU_TRACE=y. This keeps
> the memory footprint small, while still enabling CPU stall warnings
> in kernels built to enable them.
>
> Updated to include Josh Triplett's suggested use of RCU_STALL_COMMON
> config variable to simplify #if expressions.
>
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
One suggestion below; with that change,
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -486,6 +486,14 @@ config PREEMPT_RCU
> This option enables preemptible-RCU code that is common between
> the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
>
> +config RCU_STALL_COMMON
> + def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
> + help
> + This option enables RCU CPU stall code that is common between
> + the TINY and TREE variants of RCU. The purpose is to allow
> + the tiny variants to disable RCU CPU stall warnings, while
> + making these warnings mandatory for the tree variants.
> +
[...]
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -970,7 +970,7 @@ config RCU_TORTURE_TEST_RUNNABLE
>
> config RCU_CPU_STALL_TIMEOUT
> int "RCU CPU stall timeout in seconds"
> - depends on TREE_RCU || TREE_PREEMPT_RCU
> + depends on TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE
depends on RCU_STALL_COMMON
next prev parent reply other threads:[~2013-01-27 10:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-27 0:23 [PATCH tip/core/rcu 0/2] v2 Tiny RCU changes for 3.9 Paul E. McKenney
2013-01-27 0:23 ` [PATCH tip/core/rcu 1/2] rcu: Provide RCU CPU stall warnings for tiny RCU Paul E. McKenney
2013-01-27 0:23 ` [PATCH tip/core/rcu 2/2] rcu: Allow TREE_PREEMPT_RCU on UP systems Paul E. McKenney
2013-01-27 10:58 ` Josh Triplett
2013-01-27 10:57 ` Josh Triplett [this message]
2013-01-29 5:56 ` [PATCH tip/core/rcu 1/2] rcu: Provide RCU CPU stall warnings for tiny RCU Paul E. McKenney
2013-01-27 10:58 ` [PATCH tip/core/rcu 0/2] v2 Tiny RCU changes for 3.9 Josh Triplett
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