On Wed, Oct 06, 2021 at 07:53:31AM -0700, Alexei Starovoitov wrote: > On Wed, Oct 6, 2021 at 1:44 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > > > On Wed, Oct 06, 2021 at 10:41:41AM +0200, Jiri Olsa wrote: > > > hi, > > > I'm hitting performance issue and soft lock ups with the new version > > > of the patchset and the reason seems to be kallsyms lookup that we > > > need to do for each btf id we want to attach > > > > ugh, I meant to sent this as reply to the patchset mentioned above, > > nevermind, here's the patchset: > > https://lore.kernel.org/bpf/20210605111034.1810858-1-jolsa@xxxxxxxxxx/ > > > > jirka > > > > > > > > I tried to change kallsyms_lookup_name linear search into rbtree search, > > > but it has its own pitfalls like duplicate function names and it still > > > seems not to be fast enough when you want to attach like 30k functions > > > > > > so I wonder we could 'fix this' by storing function address in BTF, > > > which would cut kallsyms lookup completely, because it'd be done in > > > compile time > > > > > > my first thought was to add extra BTF section for that, after discussion > > > with Arnaldo perhaps we could be able to store extra 8 bytes after > > > BTF_KIND_FUNC record, using one of the 'unused' bits in btf_type to > > > indicate that? or new BTF_KIND_FUNC2 type? > > > > > > thoughts? > > That would be on top of your next patch set? > Please post it first. ok, will do jirka
