SysRQ-P is not always useful on SMP systems, since it usually ends up showing the
backtrace of a CPU that is doing just fine, instead of the backtrace of the CPU
that is having problems.
This patch adds SysRQ show-all-cpus(L), which shows the backtrace of every active
CPU in the system. It skips idle CPUs because some SMP systems are just too large
and we already know what the backtrace of the idle task looks like.
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
diff -up linux-2.6.25-rc3-mm1/Documentation/sysrq.txt.multicpu linux-2.6.25-rc3-mm1/Documentation/sysrq.txt
--- linux-2.6.25-rc3-mm1/Documentation/sysrq.txt.multicpu 2008-03-10 13:49:18.000000000 -0400
+++ linux-2.6.25-rc3-mm1/Documentation/sysrq.txt 2008-03-10 13:51:09.000000000 -0400
@@ -85,6 +85,8 @@ On all - write a character to /proc/sys
'k' - Secure Access Key (SAK) Kills all programs on the current virtual
console. NOTE: See important comments below in SAK section.
+'l' - Shows a stack backtrace for all active CPUs.
+
'm' - Will dump current memory info to your console.
'n' - Used to make RT tasks nice-able