Hi, (sorry for the long delay, just back from vacations)
Chunyan Zhang <[email protected]> writes: > Hi Felipe, > > On 17 May 2017 at 16:08, Felipe Balbi <[email protected]> wrote: >> >> Hi Chunyan, >> >> When you wrote your patchset to provide ftrace exports, why did you >> choose to export only function trace? Why not tracepoints, > > In fact, I tried submitting patches[1] to do exporting tracepoint to > STM, but Ingo and Steven commented that would introduce certain amount > of overhead, and that was not acceptable. I also used > 'benchmark_event' to see the additional overhead caused by printing > tracepoint message to STM. I cannot remember the exact data though, > the increased time consuming indeed was non-ignorable. > > So at the end I gave up that idea, and later on switched to the way of > implementation you see in the kernel now. Were you decoding the data before off-loading it to the trace export? Maybe that's why they consider it an extra overhead? Have you considered off-loading raw data for further post processing? >> function_graph, hwlat, irqsoff and all the other possibilities? > > I haven't thought about these clear enough :) > Any suggestion? I think we should be able to export everything and anything :-p But, of course, we would need tooling to decode it after the fact. > [1] https://lkml.org/lkml/2015/7/7/230 hmm, lkml.org seems to be down. -- balbi
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