From: Jiri Olsa <jolsa@redhat.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andriin@fb.com>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>, Daniel Xu <dxu@dxuuu.xyz>,
Viktor Malik <vmalik@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [RFC] store function address in BTF
Date: Wed, 6 Oct 2021 22:07:06 +0200 [thread overview]
Message-ID: <YV4B6nUbtCVLHbZW@krava> (raw)
In-Reply-To: <CAADnVQLeHHBsG3751Ld3--w6KEM1a+8V4KY8MReexWo+bLgdmg@mail.gmail.com>
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@redhat.com> 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@kernel.org/
> >
> > 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
next prev parent reply other threads:[~2021-10-06 20:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 8:41 [RFC] store function address in BTF Jiri Olsa
2021-10-06 8:44 ` Jiri Olsa
2021-10-06 14:53 ` Alexei Starovoitov
2021-10-06 20:07 ` Jiri Olsa [this message]
2021-10-06 16:17 ` Andrii Nakryiko
2021-10-06 20:06 ` Jiri Olsa
2021-10-06 21:22 ` Andrii Nakryiko
2021-10-06 22:05 ` Jiri Olsa
2021-10-06 22:37 ` Andrii Nakryiko
2021-10-07 6:55 ` Jiri Olsa
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