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Thu, 26 Feb 2026 10:39:10 -0800 (PST) X-Received: by 2002:a05:600c:3544:b0:47a:8383:f2b2 with SMTP id 5b1f17b1804b1-483c33f3357mr65518855e9.17.1772131150355; Thu, 26 Feb 2026 10:39:10 -0800 (PST) Received: from [127.0.0.1] ([195.174.33.230]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483bd702e7bsm181703545e9.5.2026.02.26.10.39.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 Feb 2026 10:39:10 -0800 (PST) Date: Thu, 26 Feb 2026 18:39:07 +0000 From: Gabriele Monaco To: Tejun Heo Cc: linux-kernel@vger.kernel.org, Andrea Righi , Joel Fernandes , Steven Rostedt , Nam Cao , Juri Lelli , Ingo Molnar , Peter Zijlstra , sched-ext@lists.linux.dev, Tomas Glozar , Clark Williams , John Kacur , linux-trace-kernel@vger.kernel.org Message-ID: In-Reply-To: References: <20260225095122.80683-1-gmonaco@redhat.com> <20260225095122.80683-15-gmonaco@redhat.com> <8fbc3ced19fb0c2a2171708073fa51ae308755b5.camel@redhat.com> Subject: Re: [PATCH v6 14/16] sched_ext: Export task_is_scx_enabled() for verification Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Correlation-ID: 2026-02-26T17:54:35Z Tejun Heo : > So, I don't know how rv works (searched a bit just now) but from kernel's > POV, it seems to look mostly like an additional tracing framework, and > testing p->sched_class against exported pointer value seems like a good fit > for the use case, no? It's not like task_on_scx() or state testing is going > to give you a "better" result anyway and it's actually rather confusing to > use them outside scheduler proper as these are expected to be used while the > task's rq lock is held. I don't think rv wants to (or even can) synchronize > against scheduler internals. Using external observability mechanism seems > like the better fit here. Yeah you got a gist of it, essentially RV would be running from the tracepoint contexts, so in this specific scenario it would be synchronised with the scheduler. Grabbing a pointer via kallsyms and comparing that will do exactly the same job, just a bit more "unofficially". I can do that if you think such an "official" function won't really be useful. Indeed if that function wouldn't make sense without the rq lock, tracepoints are probably the only valid use case.. Thanks, Gabriele