From: Jiri Olsa <jolsa@redhat•com>
To: Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
Andrii Nakryiko <andriin@fb•com>,
"Steven Rostedt (VMware)" <rostedt@goodmis•org>
Cc: netdev@vger•kernel.org, 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 10:44:41 +0200 [thread overview]
Message-ID: <YV1h+cBxmYi2hrTM@krava> (raw)
In-Reply-To: <YV1hRboJopUBLm3H@krava>
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?
>
> thanks,
> jirka
next prev parent reply other threads:[~2021-10-06 8:44 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 [this message]
2021-10-06 14:53 ` Alexei Starovoitov
2021-10-06 20:07 ` Jiri Olsa
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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