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From: Song Liu <songliubraving@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: open list <linux-kernel@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <Kernel-team@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Daniel Xu <dlxu@fb.com>
Subject: Re: [PATCH bpf-next 5/5] selftests/bpf: add benchmark for uprobe vs. user_prog
Date: Mon, 3 Aug 2020 04:47:47 +0000	[thread overview]
Message-ID: <DDCD362E-21D3-46BF-90A6-8F3221CBB54E@fb.com> (raw)
In-Reply-To: <CAEf4BzaP4TGF7kcmZRAKsy=oWPpFA6sUGFkctpGz-fPp+YuSOQ@mail.gmail.com>


> On Aug 2, 2020, at 6:51 PM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
> 
> On Sat, Aug 1, 2020 at 1:50 AM Song Liu <songliubraving@fb.com> wrote:
>> 
>> Add a benchmark to compare performance of
>>  1) uprobe;
>>  2) user program w/o args;
>>  3) user program w/ args;
>>  4) user program w/ args on random cpu.
>> 
> 
> Can you please add it to the existing benchmark runner instead, e.g.,
> along the other bench_trigger benchmarks? No need to re-implement
> benchmark setup. And also that would also allow to compare existing
> ways of cheaply triggering a program vs this new _USER program?

Will try. 

> 
> If the performance is not significantly better than other ways, do you
> think it still makes sense to add a new BPF program type? I think
> triggering KPROBE/TRACEPOINT from bpf_prog_test_run() would be very
> nice, maybe it's possible to add that instead of a new program type?
> Either way, let's see comparison with other program triggering
> mechanisms first.

Triggering KPROBE and TRACEPOINT from bpf_prog_test_run() will be useful. 
But I don't think they can be used instead of user program, for a couple
reasons. First, KPROBE/TRACEPOINT may be triggered by other programs 
running in the system, so user will have to filter those noise out in
each program. Second, it is not easy to specify CPU for KPROBE/TRACEPOINT,
while this feature could be useful in many cases, e.g. get stack trace 
on a given CPU. 

Thanks,
Song

  reply	other threads:[~2020-08-03  4:48 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01  8:47 [PATCH bpf-next 0/5] introduce BPF_PROG_TYPE_USER Song Liu
2020-08-01  8:47 ` [PATCH bpf-next 1/5] bpf: " Song Liu
2020-08-01 13:58   ` kernel test robot
2020-08-01 15:21   ` kernel test robot
2020-08-06 18:18   ` kernel test robot
2020-08-06 18:18   ` [RFC PATCH] bpf: user_verifier_ops can be static kernel test robot
2020-08-01  8:47 ` [PATCH bpf-next 2/5] libbpf: support BPF_PROG_TYPE_USER programs Song Liu
2020-08-03  1:40   ` Andrii Nakryiko
2020-08-03  4:21     ` Song Liu
2020-08-03  5:05       ` Andrii Nakryiko
2020-08-04  1:18     ` Song Liu
2020-08-05  1:38       ` Andrii Nakryiko
2020-08-05  3:59         ` Song Liu
2020-08-05  5:32           ` Andrii Nakryiko
2020-08-05  6:26             ` Song Liu
2020-08-05  6:54               ` Andrii Nakryiko
2020-08-05  7:23                 ` Song Liu
2020-08-05 17:44                   ` Andrii Nakryiko
2020-08-01  8:47 ` [PATCH bpf-next 3/5] selftests/bpf: add selftest for BPF_PROG_TYPE_USER Song Liu
2020-08-03  1:43   ` Andrii Nakryiko
2020-08-03  4:33     ` Song Liu
2020-08-03  5:07       ` Andrii Nakryiko
2020-08-01  8:47 ` [PATCH bpf-next 4/5] selftests/bpf: move two functions to test_progs.c Song Liu
2020-08-03  1:46   ` Andrii Nakryiko
2020-08-03  4:34     ` Song Liu
2020-08-01  8:47 ` [PATCH bpf-next 5/5] selftests/bpf: add benchmark for uprobe vs. user_prog Song Liu
2020-08-03  1:51   ` Andrii Nakryiko
2020-08-03  4:47     ` Song Liu [this message]
2020-08-03  5:10       ` Andrii Nakryiko
2020-08-04 20:54         ` Song Liu
2020-08-05  1:52           ` Andrii Nakryiko
2020-08-05  4:47             ` Song Liu
2020-08-05  5:47               ` Andrii Nakryiko
2020-08-05  7:01                 ` Song Liu
2020-08-05 17:39                   ` Andrii Nakryiko
2020-08-05 18:41                     ` Song Liu
2020-08-05 17:16               ` Alexei Starovoitov
2020-08-05 17:27                 ` Andrii Nakryiko
2020-08-05 17:45                   ` Alexei Starovoitov
2020-08-05 17:56                     ` Andrii Nakryiko
2020-08-05 18:56                 ` Song Liu
2020-08-05 22:50                   ` Alexei Starovoitov
2020-08-05 23:50                     ` Song Liu

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