* jerome zh ([email protected]) wrote: > 2010/6/2 Mathieu Desnoyers <[email protected]> > > > > * jerome zh ([email protected]) 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. > > I'm sorry but what do you mean by "_not_ pretty-printing"
By keeping data in binary format rather than text-based. > and "output > the information at high volume using LTTng, but expect to use an > output different from the console." Don't use a serial console to export loads of information, because the serial console is usually pretty slow. > Is lttng able to output the information immediately instead of saving > to files and check it in lttv later? You can activate a periodical timer to flush the information periodically. You can possibly create your own buffer backend that exports the data through a serial port at each event. But don't expect to be much faster than printk() if you export every event through a serial console, because this will be your bottleneck. > > > 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). > > > > I have finished this feature. Will the buffer overflow if there are > too many information to save? Please do some reading of the lttng.org website papers. The producer-consumer and flight recorder (overwrite) modes are thoroughly explained. Thanks, Mathieu > > -- > Regards, > > Jerome > -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
