On 21 March 2017 at 07:57, Chunyan Zhang <zhang.lyra@xxxxxxxxx> wrote: > On 20 March 2017 at 19:09, Alexander Shishkin > <alexander.shishkin@xxxxxxxxxxxxxxx> wrote: >> Chunyan Zhang <zhang.lyra@xxxxxxxxx> writes: >> >>> Hi Alex, >>> >>> On 20 March 2017 at 16:49, Alexander Shishkin >>> <alexander.shishkin@xxxxxxxxxxxxxxx> wrote: >>>> Hi Chunyan, >>>> >>>> A couple of clarifications: iirc this applies to the function tracer >>>> of ftrace, right? Does it make sense to mention that? Also, are you >>> >>> Right, only applies to the function tracer currently (actually only >>> function address and parent function address of Function tracer is >>> recorded into STM, I mean it doesn't include like "pid" "task name" >>> "cpu-id" these information right now). It makes sense to mention >>> function tracer, I will address that. >> >> Thanks! >> >>>> planning to support other ftrace payloads like trace_printk()s? >>> >>> No plan so far, but I think I can consider to do that, it depends on >>> how many people think that are helpful. >>> What do you think? >> >> Well, I myself almost never use function tracer, but I do use >> tracepoints/trace_printk()s. I'm *guessing* that everybody who's > > In fact I had implemented exporting tracepoints to STM and tried > upstreaming that, but Steven Rostedt and Ingo expressed their worries > on that would introduce a considerable impact on Ftrace fast path > since a tracepoint basically was a string which was too long to be > written to STM with some acceptable impact on fast path, so I stopped > upstreaming that feature. Did we ever consider writing a string pointer (or even on offset into the corresponding section, to avoid KASLR fun) instead of the actual string? This would require a kernel binary on the decoding end, though. Regards, -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
