Messages in this thread |  | | | From | hp <> | | Subject | Re: [patch] trace: Add user-space event tracing/injection | | Date | Thu, 18 Nov 2010 16:25:09 +0000 (UTC) |
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Ingo Molnar <mingo <at> elte.hu> writes:
> > > * Darren Hart <dvhart <at> linux.intel.com> wrote: > > > Ideally I would like to see something just like trace_printf() > > without having to define it myself in each of my testcases. [...] > > We can make the prctl a single-argument thing, at the cost of not allowing \0 in the > content. (which is probably sane anyway) > > That way deployment is super-simple: > > prctl(35, "My Trace Message"); > ... > > if (asprintf(&msg, "My Trace Message: %d\n", 1234) != -1) { > prctl(35, *msg); > free(*msg); > } > > Thanks, > > Ingo > I like this approach - it is doing it nearly the same way I did it with an extra k-mod (no patch needed) and a debugfs entry handled in that mod. I only see one thing with the string only data - I am doing stuff where there are long recording times with also a lot of user events, in such an environment I need more semantics on the event contents. In my k-mod solution there's an event ID and the opportunity to log binary data. As prctl() has 4 additional args after the option, it would be possible to use it in the following way: prtctl( 35, int eventID, int data_type, int msglen, void *buf); or without the data_type prtctl( 35, int eventID, int msglen, void *buf); decoding would be of more effort but it would be worth
The event definition would be like this (with data_type):
TRACE_EVENT(user, TP_PROTO(int id, int dtype, int dlen, unsigned char *bytes), TP_ARGS(id, dtype, dlen, bytes), TP_STRUCT__entry( __field(int, ev_id) __field(int, ev_type) __dynamic_array(unsigned char, ev_data, dlen) ), TP_fast_assign( __entry->ev_id = id; __entry->ev_type = dtype; memcpy(__get_dynamic_array(ev_data), bytes, dlen); ),
TP_printk("ID: %d type: %s data: %s", __entry->ev_id, __print_symbolic(__entry->ev_type, {0,"V"}, {1,"I"}, {2,"S"}, {4,"B"}), __entry->ev_type == 0 ? "n/a" : __get_str(ev_data)) );
What do you think about this? /hp
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