On Wed, 10 Jul 2019 21:32:25 +0200 Daniel Borkmann <dan...@iogearbox.net> wrote:
> Looks like you missed Brendan Gregg's prior feedback from v1 [0]. I haven't > seen a strong compelling argument for why this needs to reside in the kernel > tree given we also have all the other tracing tools and many of which also > rely on BPF such as bcc, bpftrace, ply, systemtap, sysdig, lttng to just name > a few. Given all the other tracers manage to live outside the kernel tree just > fine, so can dtrace as well; it's _not_ special in this regard in any way. It > will be tons of code in long term which is better off in its separate project, > and if we add tools/dtrace/, other projects will come as well asking for > kernel > tree inclusion 'because tools/dtrace' is now there, too. While it totally > makes > sense to extend the missing kernel bits where needed, it doesn't make sense to > have another big tracing project similar to perf in the tree. Therefore, I'm > not applying this patch, sorry. I agree with this. Note, trace-cmd is very tied to ftrace just as much as perf is to the code in tree. There was a window in time I had a choice to add it to tools/ as well, but after careful consideration, I decided it's best against it. The only thing being in tree gives you is marketing. Otherwise, it makes it too coupled. I keep having to compile perf separately, because a lot of perf distro packages appear to think that it requires the same kernel version. It also makes it easier to have your own release cycles, otherwise it forces you to be on a 2 1/2 month cycle that the kernel is on. And it forces you to have a clear separation between kernel and user space. That said, I'm working to put together libraries that interact with all the current tracers (perf, trace-cmd, lttng, bpftrace, etc) and call it the "Unified Tracing Platform". The purpose is to allow any tool to be able to take advantage of any of the supported tracers within the running kernel. This will be one of the topics at the Tracing MC at Linux Plumbers in September. I hope to see all of you there ;-) -- Steve
