From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: "Jiri Olsa" <jolsa@kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andriin@fb.com>,
Networking <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>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Jesper Brouer" <jbrouer@redhat.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
"Viktor Malik" <vmalik@redhat.com>
Subject: Re: [RFC bpf-next 07/16] kallsyms: Use rb tree for kallsyms name search
Date: Thu, 29 Oct 2020 10:33:43 +0100 [thread overview]
Message-ID: <20201029093343.GB3027684@krava> (raw)
In-Reply-To: <CAEf4BzarrQLrh4PXZvMmrL8KpBTjB65V9+jxn0os-Yd2jN2aYQ@mail.gmail.com>
On Wed, Oct 28, 2020 at 03:40:46PM -0700, Andrii Nakryiko wrote:
> On Wed, Oct 28, 2020 at 3:29 PM Jiri Olsa <jolsa@redhat.com> wrote:
> >
> > On Thu, Oct 22, 2020 at 10:21:29AM +0200, Jiri Olsa wrote:
> > > The kallsyms_expand_symbol function showed in several bpf related
> > > profiles, because it's doing linear search.
> > >
> > > Before:
> > >
> > > Performance counter stats for './src/bpftrace -ve kfunc:__x64_sys_s* \
> > > { printf("test\n"); } i:ms:10 { printf("exit\n"); exit();}' (5 runs):
> > >
> > > 2,535,458,767 cycles:k ( +- 0.55% )
> > > 940,046,382 cycles:u ( +- 0.27% )
> > >
> > > 33.60 +- 3.27 seconds time elapsed ( +- 9.73% )
> > >
> > > Loading all the vmlinux symbols in rbtree and and switch to rbtree
> > > search in kallsyms_lookup_name function to save few cycles and time.
> > >
> > > After:
> > >
> > > Performance counter stats for './src/bpftrace -ve kfunc:__x64_sys_s* \
> > > { printf("test\n"); } i:ms:10 { printf("exit\n"); exit();}' (5 runs):
> > >
> > > 2,199,433,771 cycles:k ( +- 0.55% )
> > > 936,105,469 cycles:u ( +- 0.37% )
> > >
> > > 26.48 +- 3.57 seconds time elapsed ( +- 13.49% )
> > >
> > > Each symbol takes 160 bytes, so for my .config I've got about 18 MBs
> > > used for 115285 symbols.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> >
> > FYI there's init_kprobes dependency on kallsyms_lookup_name in early
> > init call, so this won't work as it is :-\ will address this in v2
> >
> > also I'll switch to sorted array and bsearch, because kallsyms is not
> > dynamically updated
>
> what about kernel modules then?
please check my answer to Alexei, I just answered it there
thanks,
jirka
>
> >
> > jirka
> >
> > > ---
> > > kernel/kallsyms.c | 95 ++++++++++++++++++++++++++++++++++++++++++-----
> > > 1 file changed, 86 insertions(+), 9 deletions(-)
> > >
>
> [...]
>
next prev parent reply other threads:[~2020-10-29 9:34 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 8:21 [RFC bpf-next 00/16] bpf: Speed up trampoline attach Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 01/16] ftrace: Add check_direct_entry function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 02/16] ftrace: Add adjust_direct_size function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 03/16] ftrace: Add get/put_direct_func function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 04/16] ftrace: Add ftrace_set_filter_ips function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 05/16] ftrace: Add register_ftrace_direct_ips function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 06/16] ftrace: Add unregister_ftrace_direct_ips function Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 07/16] kallsyms: Use rb tree for kallsyms name search Jiri Olsa
2020-10-28 18:25 ` Jiri Olsa
2020-10-28 21:15 ` Alexei Starovoitov
2020-10-29 9:29 ` Jiri Olsa
2020-10-29 22:45 ` Andrii Nakryiko
2020-10-28 22:40 ` Andrii Nakryiko
2020-10-29 9:33 ` Jiri Olsa [this message]
2020-10-22 8:21 ` [RFC bpf-next 08/16] bpf: Use delayed link free in bpf_link_put Jiri Olsa
2020-10-23 19:46 ` Andrii Nakryiko
2020-10-25 19:02 ` Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 09/16] bpf: Add BPF_TRAMPOLINE_BATCH_ATTACH support Jiri Olsa
2020-10-23 20:03 ` Andrii Nakryiko
2020-10-23 20:31 ` Steven Rostedt
2020-10-23 22:23 ` Andrii Nakryiko
2020-10-25 19:41 ` Jiri Olsa
2020-10-26 23:19 ` Andrii Nakryiko
2020-10-22 8:21 ` [RFC bpf-next 10/16] bpf: Add BPF_TRAMPOLINE_BATCH_DETACH support Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 11/16] bpf: Sync uapi bpf.h to tools Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 12/16] bpf: Move synchronize_rcu_mult for batch processing (NOT TO BE MERGED) Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 13/16] libbpf: Add trampoline batch attach support Jiri Olsa
2020-10-23 20:09 ` Andrii Nakryiko
2020-10-25 19:11 ` Jiri Olsa
2020-10-26 23:15 ` Andrii Nakryiko
2020-10-27 19:03 ` Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 14/16] libbpf: Add trampoline batch detach support Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 15/16] selftests/bpf: Add trampoline batch test Jiri Olsa
2020-10-22 8:21 ` [RFC bpf-next 16/16] selftests/bpf: Add attach batch test (NOT TO BE MERGED) Jiri Olsa
2020-10-22 13:35 ` [RFC bpf-next 00/16] bpf: Speed up trampoline attach Steven Rostedt
2020-10-22 14:11 ` Jiri Olsa
2020-10-22 14:42 ` Steven Rostedt
2020-10-22 16:21 ` Steven Rostedt
2020-10-22 20:52 ` Steven Rostedt
2020-10-23 6:09 ` Jiri Olsa
2020-10-23 13:50 ` Steven Rostedt
2020-10-25 19:01 ` Jiri Olsa
2020-10-27 4:30 ` Alexei Starovoitov
2020-10-27 13:14 ` Steven Rostedt
2020-10-27 14:28 ` Jiri Olsa
2020-10-28 21:13 ` Alexei Starovoitov
2020-10-29 11:09 ` Jiri Olsa
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