On Wed, Mar 5, 2025 at 11:47 AM David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> On 05.03.25 20:43, Andrii Nakryiko wrote:
> > On Wed, Mar 5, 2025 at 7:22 AM Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> >>
> >> On 03/04, David Hildenbrand wrote:
> >>>
> >>> Currently, uprobe_write_opcode() implements COW-breaking manually, which is
> >>> really far from ideal.
> >>
> >> To say at least ;)
> >>
> >> David, thanks for doing this. I'll try to read 3/3 tomorrow, but I don't
> >> think I can really help. Let me repeat, this code was written many years
> >> ago, I forgot everything, and today my understanding of mm/ is very poor.
> >> But I'll try anyway.
> >>
> >>> Are there any uprobe tests / benchmarks that are worth running?
> >>
> >> All I know about uprobe tests is that bpf people run a lot of tests which
> >> use uprobes.
> >>
> >> Andrii, Jiri, what you advise?
> >>
> >
> > We do have a bunch of tests within BPF selftests:
> >
> > cd tools/testing/selftest/bpf && make -j$(nproc) && sudo ./test_progs -t uprobe
>
> I stumbled over them, but was so far not successful in building them in
> my test VM (did not try too hard, though). Will try harder now that I
> know that it actually tests uprobe properly :)
If you have decently recent Clang and pahole, then just make sure you
have kernel built before you build selftests. So above instructions
are more like:
1. cd <linux-repo>
2. cat tools/testing/selftests/bpf/{config, config.<your_arch>} >> .config
3. make -j$(nproc) # build kernel with that adjusted config
4. cd tools/testing/selftests/bpf
5. make -j$(nproc) # build BPF selftests
6. sudo ./test_progs -t uprobe # run selftests with "uprobe" in their name
>
> >
> > I also built an uprobe-stress tool to validate uprobe optimizations I
> > was doing, this one is the most stand-alone thing to use for testing,
> > please consider checking that. You can find it at [0], and see also
> > [1] and [2] where I was helping Peter to build it from sources, so
> > that might be useful for you as well, if you run into problems with
> > building. Running something like `sudo ./uprobe-stress -a10 -t5 -m5
> > -f3` would hammer on this quite a bit.
>
> Thanks, I'll play with that as well.
>
> >
> > I'm just about to leave on a short vacation, so won't have time to go
> > over patches, but I plan to look at them when I'm back next week.
> >
> > [0] https://github.com/libbpf/libbpf-bootstrap/tree/uprobe-stress
> > [1] https://lore.kernel.org/linux-trace-kernel/CAEf4BzZ+ygwfk8FKn5AS_Ny=igvGcFzdDLE2FjcvwjCKazEWMA@xxxxxxxxxxxxxx/
> > [2] https://lore.kernel.org/linux-trace-kernel/CAEf4BzZqKCR-EQz6LTi-YvFY4RnYb_NnQXtwgZCv6aUo7gjkHg@xxxxxxxxxxxxxx
> >
> >> Oleg.
> >>
> >
>
>
> --
> Cheers,
>
> David / dhildenb
>
