Re: [PATCH v2] rust_binder: speed up get_node_debug_info using lower_bound iter

[Alice Ryhl <aliceryhl@google.com>]

On Fri, Jul 31, 2026 at 10:31:03AM -0300, Rafael Passos wrote:
> Finding the next node in the RBTree can be done more efficiently using
> the cursor_lower_bound, as it reduces cost from O(n) to O(log n).
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1249
> Suggested-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Rafael Passos <rafael@rcpassos.me>

This looks fine to me.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

> It took me a while to get the AOSP + Cuttlefish setup running, and
> using the rust binder module. I got it working, and ran:
> libhwbinder_benchmark libbinder_benchmark, hwbinderThroughputTest
>             libhwbinder_latency and binderThroughputTest benches.
> But apparently none of them used the function I touched (I added log).
> Also, the "hw" variants like hwbinderThroughputTest kept logging a
>  "worker_fx:217 condition:service->isRemote() failed" message.
> I decided to send the v2 anyway.
> 
> I am thinking about writing a benchmark focused on node scaling
>     (test N iterations with X nodes), and run with small and larger Xs.)
> Would such a benchmark be welcome here in upstream mainline ?
> It would be in either C or Rust (the AOSP ones are in C++).
> Would it live under `tools/perf` ?
> 
> I looked at the kunit tests (`drivers/android/tests`) and they dont
> cover the rust binder either. That's another thing I could try to add.

In Android this is used by libmemunreachable when checking whether a
process has a memory leak. The perf matters because if the number of
nodes is very large, invoking the ioctl repeatedly many times could take
a seriously large amount of time. Seconds or even more.

Alice