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Mon, 19 Oct 2026 03:48:04 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([195.174.134.4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1bd9b8b5fsm397495935e9.9.2026.10.19.03.48.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 03:48:03 -0700 (PDT) Message-ID: Subject: Re: [PATCH v2 10/15] tools/rv: Add BPF monitors From: Gabriele Monaco To: John Ogness , Alexei Starovoitov , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Steven Rostedt Cc: Nam Cao , Wen Yang , Tobias Schaffner , Viktor Malik Date: Mon, 19 Oct 2026 12:48:02 +0200 In-Reply-To: <871p9mqcn2.fsf@jogness.linutronix.de> References: <20261001152042.124445-1-gmonaco@redhat.com> <20261001152042.124445-11-gmonaco@redhat.com> <878q3xtptq.fsf@jogness.linutronix.de> <8B3FF026-6159-48CF-8FEA-AF2FACD2E4EB@redhat.com> <87bj8s8ih9.fsf@jogness.linutronix.de> <871p9mqcn2.fsf@jogness.linutronix.de> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0BrZXJuZWwub3JnPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmjKX2MCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfIQuAD+JulczTN6l7oJjyroySU55Fbjdvo52xiYYlMjPG7dCTsBAMFI7dSL5zg98I+8 cXY1J7kyNsY6/dcipqBM4RMaxXsOtCRHYWJyaWVsZSBNb25hY28gPGdtb25hY29AcmVkaGF0LmNvb T6InAQTFgoARAIbAwUJBaOagAULCQgHAgIiAgYVCgkICwIEFgIDAQIeBwIXgBYhBMrKEfgLgd0WcK eo9u9KbElYeE3yBQJoymCyAhkBAAoJEO9KbElYeE3yjX4BAJ/ETNnlHn8OjZPT77xGmal9kbT1bC1 7DfrYVISWV2Y1AP9HdAMhWNAvtCtN2S1beYjNybuK6IzWYcFfeOV+OBWRDQ== Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.2 (3.60.2-2.fc44) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Mon, 2026-10-19 at 11:16 +0206, John Ogness wrote: > On 2026-10-19, Gabriele Monaco wrote: > > > > We are missing stack traces (which I'd optionally add only on error= s) > > > > and perhaps other events (e.g. the -e in either tool if you aren't > > > > only interested in errors/events of the monitor). > > >=20 > > > I don't see the point of reinventing tools that already do the job > > > well. I do not mind if developers want to create their own tools that > > > provide some small subset of existing features. But I am concerned > > > about removing the in-kernel RV support for ftrace and perf. > >=20 > > That's valid too. We'd need at least the rv tool to start/stop > > monitors in addition to ftrace/perf. Kind of what you already do now > > with sysfs. >=20 > I do not expect the rv tool to start/stop ftrace/perf. Nor would I > consider that useful. When I am using ftrace/perf, I am interested in > additionally related events. The rv tool can not know what what else I > need and I do not want the rv tool to become a wrapper for ftrace/perf. Yeah of course, I meant more that you need to call both tools (start the mo= nitor /and/ the tracing). At most I'd have a -e flag in rv (just like rtla has, mirroring trace-cmd functionality). But you're right, it's best if the other tools can do that first. >=20 > I would use the rv tool only to start the monitor. It would be enough if > the tool would report the bpf_trace:bpf_trace_printk globs that are > needed for the various possible violations. Then, with the monitor > started, I would start ftrace/perf for my own investigations (also > capturing any violation events). >=20 That's an interesting idea actually. Thanks, Gabriele