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Mon, 12 Oct 2026 04:47:12 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([195.174.135.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48db9abd57fsm18489239f8f.37.2026.10.12.04.47.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Oct 2026 04:47:11 -0700 (PDT) Message-ID: <4759c9b0dacdf1f9c0cf47158895860dbd0ec401.camel@redhat.com> Subject: Re: [PATCH v2 0/3] rv: per-edge dwell-time statistics for per-cpu monitors From: Gabriele Monaco To: Tobias Schaffner , Steven Rostedt Cc: Jonathan Corbet , Shuah Khan , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, rpm@xenomai.org, jan.kiszka@siemens.com Date: Mon, 12 Oct 2026 13:47:09 +0200 In-Reply-To: <20260911123439.463052-1-tobias.schaffner@siemens.com> References: <20260911123439.463052-1-tobias.schaffner@siemens.com> 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 Fri, 2026-09-11 at 14:34 +0200, Tobias Schaffner wrote: > Hi Steven, Gabriele, >=20 > I am using the RV system for a downstream project called EVL (aka Xenomai= 4). > It is a small co-kernel system, small enough that I can model the whole > co-kernel with RV instead of just a fragment of it. >=20 > The patches in this series add a per-monitor "stats" file that exposes ho= w > often an edge has been visited and the dwell time in the prior state for > per-cpu monitors. >=20 > This allows me to not only check if the model is correct but also to see = if > all paths are exercised by my stress tooling and to decompose the latency= of > the co-kernel's wakeup path. >=20 > I think that some of the upstream monitors like e.g. the sts monitor coul= d > also profit from this. Hi Tobias, there's been a conversation at LPC about completely migrating RV to BPF. While we aren't sure of its feasibility yet, and it will take time, it's something to keep in mind for new contributions. First of all, would dropping RV in-kernel support negatively affect your cu= rrent workflow? About this series, I believe we could implement the same using BPF maps wit= hout too much effort, then the rv userspace tool could display them nicely. What do you think? Thanks, Gabriele