| From | Namhyung Kim <> | Date | Thu, 12 Oct 2023 09:52:49 -0700 | Subject | Re: [RFC 00/48] perf tools: Introduce data type profiling (v1) |
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On Thu, Oct 12, 2023 at 2:17 AM Peter Zijlstra <peterz@infradead.org> wrote: > > On Wed, Oct 11, 2023 at 08:50:23PM -0700, Namhyung Kim wrote: > > > Actually there's a performance issue about getting disassembly from the > > objdump for kernel. On my system, GNU objdump was really slower than the > > one from LLVM for some reason so I had to pass the following option for > > each perf report and perf annotate. > > > > $ sudo perf report --objdump=llvm-objdump ... > > > > # To save it in the config file and drop the command line option > > $ sudo perf config annotate.objdump=llvm-objdump > > > > Even with this change, still the most processing time was spent on the > > objdump to get the disassembly. It'd be nice if we can get the result > > without using objdump at all. > > So the kernel has an instruction decoder, all we need is something that > can pretty print the result. IIRC Masami had an early version of that > somewhere. > > With those bits, and some basic ELF parsing (find in objtool for > instance) you can implement most of objdump yourself.
That would be nice, but I'm a bit afraid of dealing with details of instruction decoding especially for unusual ones considering extensibility to user space and other architectures.
Thanks, Namhyung
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