[ltt-dev] Is Lttng able to work as a printk-like function？

[Mathieu Desnoyers]

* jerome zh (jeromezhr at gmail.com) wrote:
> Hi all,
> 
> In our projects, we used to call printk() in the ip stack to show some ip
> header information each time a packet comes in.
> But when the packet comes too frequently, the system becomes overload
> because of  too many printk().
> So we are wondering if we can do this by lttng, since its performance is
> quite high?

LTTng achieve high throughput by _not_ pretty-printing all the
information to the console like printk() does. So you can output the
information at high volume using LTTng, but expect to use an output
different from the console.

If you want to save printk-like information to the trace (e.g.
format-string based calls), you should use the "trace_mark()" statements
(Markers).

Thanks,

Mathieu

> If lttng cannot directly print them to the screen,  recording ip header
> information to the trace files is also a good choice.
> 
> BTW, I've read the marker.txt and tracepoint.txt. But these examples don't
> cover such subject.
> 
> Any suggestions? Thanks in advance.
> 
> -- 
> Regards,
> 
> Jerome

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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com