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[5.90.98.35]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48b380f0613sm8640050f8f.13.2026.10.02.12.40.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Oct 2026 12:40:21 -0700 (PDT) Date: Fri, 02 Oct 2026 19:40:19 +0000 From: Gabriele Monaco To: Peter Zijlstra CC: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Steven Rostedt , Masami Hiramatsu , Ingo Molnar , Nam Cao , K Prateek Nayak , Alexei Starovoitov , Wen Yang , Tobias Schaffner , Viktor Malik Subject: Re: [PATCH v2 01/15] sched: Add task enqueue/dequeue trace points In-Reply-To: <20261002191842.GA1259248@noisy.programming.kicks-ass.net> References: <20261001152042.124445-1-gmonaco@redhat.com> <20261001152042.124445-2-gmonaco@redhat.com> <20261001154934.GT88198@noisy.programming.kicks-ass.net> <20261002102939.GB2823843@noisy.programming.kicks-ass.net> <56972260b9221128d7aaf5bb60f90611ec9d7235.camel@redhat.com> <20261002191842.GA1259248@noisy.programming.kicks-ass.net> Message-ID: <6BEABF91-8CA6-4859-A426-D65F3CC6E13B@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 8pNLToDbZt851U_AO4Mw3zwHAsFdSp_OGLOwVFh-ZoQ_1790970022 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Il 2 ottobre 2026 19:18:42 UTC, Peter Zijlstra ha sc= ritto: >On Fri, Oct 02, 2026 at 01:55:48PM +0200, Gabriele Monaco wrote: >> On Fri, 2026-10-02 at 12:29 +0200, Peter Zijlstra wrote: >> > So mostly I flat out out ignore partial series. It means I have to go >> > dig around to figure out the whole picture, and anything that requires >> > extra effort goes on the 'later' pile, and you know where that lives. >>=20 >> Alright, I guess I'm going to have to fix my to_cmd script. >>=20 >> > Now, as to 3,4; I'm confused. If I search 'enqueue' I see there is a >> > tracepoint attach thingy in the .c file, but I don't see the >> > corresponding bits in the .dot file. And per my understanding the .c >> > thing is an artifact of the .dot file. >>=20 >> Yes but only partially. There isn't always a 1-1 mapping with model even= ts and >> tracepoints. > >So the .c files are no longer an artifact? That seems unfortunate. I >thought the .dot file was fully descriptive and the .c file was fully >generated by dot2c. > >If we cannot fully express the automaton in .dot, we should look at >extending the 'format' and teach dot2c new tricks. The linking between events and tracepoint has always been manual, but yeah,= it would be nice to describe the whole thing in the specification. Though that would require quite a bit of work, deadline and LTL monitors ha= ve some more complicated mapping. > >> Throttle uses handle_sched_enqueue() for one case of dl_defer_arm, repre= senting >> a fair task running not boosted, in the enqueue case, because it was run= ning >> with another scheduler. >> Boost uses handle_sched_dequeue() in a similar fashion to describe fair = tasks >> that stop running on the fair runqueue (but may continue on another runq= ueue). >>=20 >> In both cases I'm reusing an event that can be triggered from other trac= epoints >> too, ideally to keep the model simpler. >>=20 >> Then it uses handle_sched_enqueue() for dl_server_resume[_throttled]. Th= ey are >> both plain enqueues, in fact, so I could rename them to show what they a= re. > >I'm not sure I'm following. Will you be in Prague next week? > Yes I'll be there. We can definitely discuss this better. Thanks, Gabriele >> > Also, IMO it would be *much* preferred if the .rst file would not exis= t. >> > Just have the graph-easy and the description as a comment in the .dot >> > file. Then you have the whole thing in one *readable* place. >>=20 >> Well, you make a fair point, I like to have it appear in the html docs, = but >> obviously no one is going to build the docs to review a patch. >> I may look into ways to get both birds with a stone. > >So personally I have 0 interest or use for html. Mail is text, code is >text, we use a text editor (neovim is my current poison of choice). >Nowhere is there html. So then having to look at rst is just crap. rst >gets in the way of actually reading the thing. All down-sides, no >up-sides. >