Messages in this thread | | | Date | Tue, 16 Dec 2008 23:16:28 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [ltt-dev] [PATCH] Simple LTTng userspace events through debugfs |
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* Ingo Molnar (mingo@elte.hu) wrote: > > * Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote: > > > Hi, > > > > I looked at kmemtrace and noticed that the presence of a debugfs > > "marker" file, which lets userspace write events into the trace buffers. > > > > So I just did the same with a > > > > /debugfs/ltt/write_event > > you mean similar to ftrace's /debug/tracing/trace_marker ? ;-) >
Quite similar, yes :)
Looking at tracing_mark_write(), I am wondering if the fact that it returns a count including the added \n is an expected side effect ? A write() returning a count larger than the number of bytes written seems to be a bit unexpected... But if we remove the \n from the count, then the case where one write \0 into the event content would end up doing an endless loop.
Mathieu
> Ingo > > _______________________________________________ > ltt-dev mailing list > ltt-dev@lists.casi.polymtl.ca > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev >
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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