rcu: add boot parameter to suppress RCU CPU stall warning messages
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From: Josh Triplett on 14 Jul 2010 17:30 On Wed, Jul 14, 2010 at 01:10:03PM -0700, Paul E. McKenney wrote: > Although the RCU CPU stall warning messages are a very good way to alert > people to a problem, once alerted, it is sometimes helpful to shut them > off in order to avoid obscuring other messages that might be being used > to track down the problem. Although you can rebuild the kernel with > CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient. This > commit therefore adds a boot parameter named "rcu_cpu_stall_suppress" > that shuts these messages off without requiring a rebuild (though a > reboot might be needed for those not brave enough to patch their kernel > while it is running). > > This message-suppression was already in place for the panic case, so this > commit need only rename the variable and export it via module_param(). > > Signed-off-by: Paul E. McKenney <paulmck(a)linux.vnet.ibm.com> > --- > kernel/rcutree.c | 11 ++++++++--- > 1 files changed, 8 insertions(+), 3 deletions(-) > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > index 5b1c3c2..f3d5906 100644 > --- a/kernel/rcutree.c > +++ b/kernel/rcutree.c > @@ -143,6 +143,11 @@ module_param(blimit, int, 0); > module_param(qhimark, int, 0); > module_param(qlowmark, int, 0); > > +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR > +int rcu_cpu_stall_suppress __read_mostly; > +module_param(rcu_cpu_stall_suppress, int, 0); > +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ In theory, you could change the permissions on this module_param from 0 to 0644, making it appear under /sys as a writable file. That would allow changing it at runtime rather than just at boot time. Looking at the use of this variable, changing it dynamically should work. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Paul E. McKenney on 14 Jul 2010 19:40
On Wed, Jul 14, 2010 at 02:16:06PM -0700, Josh Triplett wrote: > On Wed, Jul 14, 2010 at 01:10:03PM -0700, Paul E. McKenney wrote: > > Although the RCU CPU stall warning messages are a very good way to alert > > people to a problem, once alerted, it is sometimes helpful to shut them > > off in order to avoid obscuring other messages that might be being used > > to track down the problem. Although you can rebuild the kernel with > > CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient. This > > commit therefore adds a boot parameter named "rcu_cpu_stall_suppress" > > that shuts these messages off without requiring a rebuild (though a > > reboot might be needed for those not brave enough to patch their kernel > > while it is running). > > > > This message-suppression was already in place for the panic case, so this > > commit need only rename the variable and export it via module_param(). > > > > Signed-off-by: Paul E. McKenney <paulmck(a)linux.vnet.ibm.com> > > --- > > kernel/rcutree.c | 11 ++++++++--- > > 1 files changed, 8 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/rcutree.c b/kernel/rcutree.c > > index 5b1c3c2..f3d5906 100644 > > --- a/kernel/rcutree.c > > +++ b/kernel/rcutree.c > > @@ -143,6 +143,11 @@ module_param(blimit, int, 0); > > module_param(qhimark, int, 0); > > module_param(qlowmark, int, 0); > > > > +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR > > +int rcu_cpu_stall_suppress __read_mostly; > > +module_param(rcu_cpu_stall_suppress, int, 0); > > +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ > > In theory, you could change the permissions on this module_param from 0 > to 0644, making it appear under /sys as a writable file. That would > allow changing it at runtime rather than just at boot time. Looking at > the use of this variable, changing it dynamically should work. Will give it a try! Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |