Messages in this thread | | | Date | Tue, 19 May 2015 22:14:53 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [RFC PATCH v3 00/37] perf tools: introduce 'perf bpf' command to load eBPF programs. |
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Em Tue, May 19, 2015 at 06:02:13PM -0700, Alexei Starovoitov escreveu: > On 5/19/15 3:05 PM, Arnaldo Carvalho de Melo wrote: > > > >Ok, can you point me to this bpf_file.c, an example? So that we can talk > >about the parts of it that would be short circuited when not loading the > >bpf_file.o, etc.
Thanks! I'll continue tomorrow, reading those examples as well messages I saw on netdev.
- Arnaldo
> There are different use cases that would fit in different perf commands. > - 1st use case is quick kernel debugging which could be something > similar to: samples/bpf/tracex1_kern.c > where the user would type a little program with some filtering and > printing and will say 'perf script prog.c' > where it would compile (in microseconds), load, hook into kernel > and print stuff to the screen. > If it prints too much, the user will just Ctrl-C, tweak the prog > and repeat. > I'm seeing it as replacement of 'add printk to kernel, recompile, > reboot' cycle. > > - 2nd use case is performance analysis of various things where > aggregation is happening in the kernel and data is printed by > user space in human friendly way. There are three main categories > of visualization: histograms, heatmaps, flamegraphs. > The program will collect the data into such structures > and perf will be visualizing them. > Currently tracex2 is an example of histogram, tracex3 - heatmap > and flamegraphs in the works. > > - 3rd use case is 'top' like visualization > tracex4 example is trying to demo it. > > these are my use cases. > - Wang's use case turned out to be 4th category. > My understanding he wants to write a program that pretty > much sophisticated filter with dependencies across multiple > events in the system and at the end visualize one 'master' > event via 'perf report'. > That's what this patch set is about. > I think 'perf record --event file.o' + 'perf report' fits > Wang's use case quite well. > My 1st use case fits 'perf script file.c' model. > How to fit 2 and 3 into perf is hard to see yet.
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