Re: [PATCH 32/32] bpf: Introduce function for outputing data to perf event
From: Wangnan (F)
Date: Fri Aug 28 2015 - 22:16:34 EST
On 2015/8/29 9:34, Alexei Starovoitov wrote:
On 8/28/15 6:19 PM, Wangnan (F) wrote:
I'd like to see whether it is possible to create dynamic tracepoints so
For me, I use bpf_output_trace_data() to output information like PMU
value. Perf is the only receiver, so global collector is perfect.
please describe your usecase in more detail?
there is a special receiver in user space that only wants the data from
the bpf program that it loaded. It shouldn't conflict with any other
processes. Like when it's running, I still should be able to use perf
for other performance analysis. There is no way to share single
bpf:bpf_output_data event, since these user processes are completely
different receivers can listen on different tracepoints. For my side, maybe
I can encode format information into the new tracepoints so don't need
those LLVM patches.
# echo 'dynamic_tracepoint:mytracepoint <encode its format>' >>
# perf list
In perf side we can encode the creation of dynamic tracepoint into
like what we currectly do for probing the kprobes.
This way reqires us to create a fresh new event source, in parallel with
tracepoint. I'm not sure
how much work it needs. What do you think?
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