(2010/11/18 3:23), Mathieu Desnoyers wrote:
quoted text
> Amongst others, Ericsson rely on this kind of feature. The case where we're
> filtering "out" should be really, really fast (even if it makes the recording
> slightly slower). If there is a race modifying the data underneath between the
> filter execution and the copy to the buffers, I really don't think it matters.
> If the tracepoint caller context don't provide data consistency guarantees for
> the parameters it passes, we should not expect 100% perfect consistency between
> filter and what is actually saved in the trace. The trace analysis tools should
> just be able to cope with that, but I really don't think anyone should care.
> 
> So I would recommend no copy, filter directly on the source data, stop the
> filter chain as soon as a non-match is observed. Copy the data into the buffers
> if the filter passes.

Indeed, so that we can eliminate memory write accesses. :)

Thanks,

-- 
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
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