# Re: \[PATCH v13 00/11\] perf: Support the deferred unwinding infrastructure

- From: Steven Rostedt \<rostedt@goodmis.org\>
- Date: 2025-07-11 20:56:53 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2025/07/3131893
- Thread: https://ratatoskr.run/linux-trace-kernel/2025/07/3124664/t.md

```text
On Fri, 11 Jul 2025 13:26:28 -0700
Namhyung Kim [ref] wrote:

> > - Removed use of timestamp. The deferred unwind has gone back to using
> >   cookies, and perf doesn't use the cookie. This means the
> >   struct perf_callchain_deferred_event is not modified.  
> 
> What about adding the cookies in the records to handle lost data?  Even
> if it's not necessary to match callchains to samples, it still needs to
> reject invalid callchains across the losts.  Maybe it can just flush
> pending samples when it sees LOST records and not try to match them but
> having the cookies will handle it more accurately as some callchains may
> be valid after the LOST.

Sure, I can add that back, with the added comments needed that Jens
suggested.

Thanks,

-- Steve
```