Re: [PATCH 21/21] tracing: Add optional percpu buffers for trace_printk()

Peter Zijlstra
2011-09-23T11:02:33Z

On Thu, 2011-09-22 at 18:09 -0400, Steven Rostedt wrote:
>
> Currently, trace_printk() uses a single buffer to write into
> to calculate the size and format needed to save the trace. To
> do this safely in an SMP environment, a spin_lock() is taken
> to only allow one writer at a time to the buffer. But this could
> also affect what is being traced, and add synchronization that
> would not be there otherwise.

so trace_printk() isn't NMI safe? #$%@^%@@$%@