Re: [PATCH v1 03/13] perf python: Lazily copy events and samples from process_events

[sashiko-bot@kernel.org]

> When perf.session.process_events() delivers an event to a Python
> callback, pyrf_event__new() previously copied the raw perf_event into a
> 4,160-byte union perf_event embedded in struct pyrf_event and called
> evsel__parse_sample() a second time to re-parse the sample against the
> copied buffer.
> 
> In the common case, the Python callback inspects the event and returns
> without storing a reference to it. Avoid the event memcpy, the duplicate
> evsel__parse_sample() call, and the large PyObject allocation by:
> 1. Storing pointers to the underlying union perf_event and
>    struct perf_sample in struct pyrf_event (using PyGetSetDef descriptors
>    backed by PyMember_GetOne() to read fields through those pointers),
>    shrinking struct pyrf_event so it fits in CPython's small-object
>    allocator pool.
> 2. Borrowing the event and pre-parsed sample pointers from
>    process_events() for the duration of the Python callback.
> 3. Checking Py_REFCNT(pyevent) > 1 after the callback returns and only
>    allocating event_copy and re-parsing into sample_storage when the
>    Python callback retained a reference to the event object (or immediately
>    in pyrf_evlist__read_on_cpu() where no pre-parsed sample is passed).
> 
> Assisted-by: Antigravity:gemini-3.1-pro
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261002182624.3259797-1-irogers@google.com?part=3