From: Michal Rostecki <mrostecki@opensuse.org>
To: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Michal Rostecki <mrostecki@opensuse.org>,
bpf@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
Jakub Kicinski <jakub.kicinski@netronome.com>,
Stanislav Fomichev <sdf@google.com>,
Peter Wu <peter@lekensteyn.nl>,
Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next v2 2/2] bpftool: Add misc secion and probe for large INSN limit
Date: Wed, 8 Jan 2020 13:41:48 +0000 [thread overview]
Message-ID: <20200108134148.GD2954@wotan.suse.de> (raw)
In-Reply-To: <70565317-89af-358f-313c-c4b327cdca4a@netronome.com>
On Tue, Jan 07, 2020 at 02:36:15PM +0000, Quentin Monnet wrote:
> Nit: typo in subject ("secion").
>
> 2020-01-07 14:03 UTC+0100 ~ Michal Rostecki <mrostecki@opensuse.org>
> > Introduce a new probe section (misc) for probes not related to concrete
> > map types, program types, functions or kernel configuration. Introduce a
> > probe for large INSN limit as the first one in that section.
> >
> > Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
> > ---
> > tools/bpf/bpftool/feature.c | 18 ++++++++++++++++++
> > 1 file changed, 18 insertions(+)
> >
> > diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
> > index 03bdc5b3ac49..d8ce93092c45 100644
> > --- a/tools/bpf/bpftool/feature.c
> > +++ b/tools/bpf/bpftool/feature.c
> > @@ -572,6 +572,18 @@ probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
> > printf("\n");
> > }
> >
> > +static void
> > +probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
> > +{
> > + bool res;
> > +
> > + res = bpf_probe_large_insn_limit(ifindex);
> > + print_bool_feature("have_large_insn_limit",
> > + "Large complexity and program size limit",
>
> I am not sure we should mention "complexity" here. Although it is
> related to program size in the kernel commit you describe, the probe
> that is run is only on instruction number. This can make a difference
> for offloaded programs: When you probe a device, if kernel has commit
> c04c0d2b968a and supports up to 1M instructions, but hardware supports
> no more than 4k instructions, you may still benefit from the new value
> for BPF_COMPLEXITY_LIMIT_INSNS for complexity, but not for the total
> number of available instructions. In that case the probe will fail, and
> the message on complexity would not be accurate.
>
> Looks good otherwise, thanks Michal!
>
> Quentin
Thanks for review! Should I change the description just to "Large
program size limit" or "Large instruction limit"?
Michal
next prev parent reply other threads:[~2020-01-08 13:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 13:03 [PATCH bpf-next v2 0/2] bpftool/libbpf: Add probe for large INSN limit Michal Rostecki
2020-01-07 13:03 ` [PATCH bpf-next v2 1/2] libbpf: " Michal Rostecki
2020-01-07 13:03 ` [PATCH bpf-next v2 2/2] bpftool: Add misc secion and " Michal Rostecki
2020-01-07 14:36 ` Quentin Monnet
2020-01-08 13:41 ` Michal Rostecki [this message]
2020-01-08 15:28 ` Quentin Monnet
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