Messages in this thread | | | Date | Tue, 4 Apr 2023 15:54:29 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v5 00/17] Reference count checker and related fixes |
| |
Em Tue, Apr 04, 2023 at 03:41:38PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Tue, Apr 04, 2023 at 08:25:41PM +0300, Adrian Hunter escreveu: > > On 4/04/23 18:58, Ian Rogers wrote: > > > Ping. It would be nice to have this landed or at least the first 10 > > > patches that refactor the map API and are the bulk of the > > > lines-of-code changed. Having those landed would make it easier to > > > rebase in the future, but I also think the whole series is ready to > > > go. > > > > I was wondering if the handling of dynamic data like struct map makes > > any sense at present. Perhaps someone can reassure me. > > > > A struct map can be updated when an MMAP event is processed. So it > > Yes, it can, and the update is made via a new PERF_RECORD_MMAP, right? > > So: > > perf_event__process_mmap() > machine__process_mmap2_event() > map__new() + thread__insert_map(thread, map) > maps__fixup_overlappings() > maps__insert(thread->maps, map); > > Ok, from this point on new samples on ] map->start .. map->end ] will > grab a refcount to this new map in its hist_entry, right? > > When we want to sort by dso we will look at hist_entry->map->dso, etc.
And in 'perf top' we go decaying hist entries, when we delete the hist_entry, drop the reference count to things it holds, that will then be finally deleted when no more hist_entries point to it.
> > seems like anything racing with event processing is already broken, and > > reference counting / locking cannot help - unless there is also > > copy-on-write (which there isn't at present)? > > > For struct maps, referencing it while simultaneously processing > > events seems to make even less sense? > > Can you elaborate some more?
- Arnaldo
| |