Re: [PATCH] tracing: Dump either the oops's cpu source or all cpus buffers

[David Miller <davem@davemloft.net>]

From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Sun, 18 Apr 2010 22:50:10 +0200

> The ftrace_dump_on_oops kernel parameter, sysctl and sysrq let one
> dump every cpu buffers when an oops or panic happens.
> 
> It's nice when you have few cpus but it may take ages if have many,
> plus you miss the real origin of the problem in all the cpu traces.
> 
> Sometimes, all you need is to dump the cpu buffer that triggered the
> opps, most of the time it is our main interest.
> 
> This patch modifies ftrace_dump_on_oops to handle this choice.
> 
> The ftrace_dump_on_oops kernel parameter, when it comes alone, has
> the same behaviour than before. But ftrace_dump_on_oops=orig_cpu
> will only dump the buffer of the cpu that oops'ed.
> 
> Similarly, sysctl kernel.ftrace_dump_on_oops=1 and
> echo 1 > /proc/sys/kernel/ftrace_dump_on_oops keep their previous
> behaviour. But setting 2 jumps into cpu origin dump mode.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

Thanks I was trying to figure out a way to make ftrace dump
do exactly this over the past few days :-)

Acked-by: David S. Miller <davem@davemloft.net>