diff options
| author | Frank Rowand <frank.rowand@am.sony.com> | 2011-09-23 13:43:12 -0700 |
|---|---|---|
| committer | Clark Williams <williams@redhat.com> | 2012-01-16 13:00:36 -0600 |
| commit | 3455718438c3b5ec2410d972df82ce16cbd9dd44 (patch) | |
| tree | b9d94679f039f5470a752585d2c224b373d8ec46 /lib | |
| parent | f1ebbaf91523565ac8be42ee9f9ca3f4fc177fe3 (diff) | |
sysrq: Allow immediate Magic SysRq output for PREEMPT_RT_FULL
Add a CONFIG option to allow the output from Magic SysRq to be output
immediately, even if this causes large latencies.
If PREEMPT_RT_FULL, printk() will not try to acquire the console lock
when interrupts or preemption are disabled. If the console lock is
not acquired the printk() output will be buffered, but will not be
output immediately. Some drivers call into the Magic SysRq code
with interrupts or preemption disabled, so the output of Magic SysRq
will be buffered instead of printing immediately if this option is
not selected.
Even with this option selected, Magic SysRq output will be delayed
if the attempt to acquire the console lock fails.
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Link: http://lkml.kernel.org/r/4E7CEF60.5020508@am.sony.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c347db3e08c2..13a937b16bfd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -62,6 +62,28 @@ config MAGIC_SYSRQ keys are documented in <file:Documentation/sysrq.txt>. Don't say Y unless you really know what this hack does. +config MAGIC_SYSRQ_FORCE_PRINTK + bool "Force printk from Magic SysRq" + depends on MAGIC_SYSRQ && PREEMPT_RT_FULL + default n + help + Allow the output from Magic SysRq to be output immediately, even if + this causes large latencies. This can cause performance problems + for real-time processes. + + If PREEMPT_RT_FULL, printk() will not try to acquire the console lock + when interrupts or preemption are disabled. If the console lock is + not acquired the printk() output will be buffered, but will not be + output immediately. Some drivers call into the Magic SysRq code + with interrupts or preemption disabled, so the output of Magic SysRq + will be buffered instead of printing immediately if this option is + not selected. + + Even with this option selected, Magic SysRq output will be delayed + if the attempt to acquire the console lock fails. + + Don't say Y unless you really know what this hack does. + config STRIP_ASM_SYMS bool "Strip assembler-generated symbols during link" default n |