Re: [PATCH bpf-next v8 2/3] perf: Refactor get_perf_callchain

[Andrii Nakryiko]

On Mon, Feb 2, 2026 at 11:59 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Fri, Jan 30, 2026 at 12:04:45PM -0800, Andrii Nakryiko wrote:
>
> > > Also, there appears to be no buildid caching what so ever, surely that
> > > would help some.
> >
> > Jiri Olsa proposed caching build id per file or per inode some time
> > back, there was vehement opposition to it. And doing some locked
> > global resizable hash that might need to be used from NMI sounds
> > horrible, tbh. So we have what we have today.
>
> See kernel/module/tree_lookup.c and include/linux/rbtree_latch.h :-)

Ah, neat idea. Each node is really two parallel nodes for each of the
latched copies. TIL, good to know and thanks!