On Wed, Mar 5, 2025 at 3:28 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote: > > The length of PERF_RECORD_KSYMBOL for BPF is a size of JITed code so > it'd be 0 when it's not JITed. The ksymbol is needed to symbolize the > code when it gets samples in the region but non-JITed code cannot get > samples. Thus it'd be ok to ignore them. > > Actually it caused a performance issue in the perf tools on old ARM > kernels where it can refuse to JIT some BPF codes. It ended up > splitting the existing kernel map (kallsyms). And later lookup for a > kernel symbol would create a new kernel map from kallsyms and then > split it again and again. :( > > Probably there's a bug in the kernel map/symbol handling in perf tools. > But I think we need to fix this anyway. > > Reported-by: Kevin Nomura <nomurak@xxxxxxxxxx> > Cc: Song Liu <song@xxxxxxxxxx> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> Acked-by: Song Liu <song@xxxxxxxxxx>
