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Wed, 11 Mar 2026 06:23:08 -0700 (PDT) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.82.96]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-439f818d61esm7352427f8f.8.2026.03.11.06.23.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Mar 2026 06:23:08 -0700 (PDT) Date: Wed, 11 Mar 2026 14:23:06 +0100 From: Juri Lelli To: Christian Loehle Cc: Shuah Khan , Peter Zijlstra , Ingo Molnar , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Valentin Schneider , Clark Williams , Gabriele Monaco , Tommaso Cucinotta , Luca Abeni , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC 5/7] selftests/sched: Add SCHED_DEADLINE bandwidth tests to kselftest Message-ID: References: <20260306-upstream-deadline-kselftests-v1-0-2b23ef74c46a@redhat.com> <20260306-upstream-deadline-kselftests-v1-5-2b23ef74c46a@redhat.com> <129bb66c-74fa-4795-8d79-6c8e10a66e17@arm.com> 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=us-ascii Content-Disposition: inline In-Reply-To: <129bb66c-74fa-4795-8d79-6c8e10a66e17@arm.com> On 11/03/26 09:31, Christian Loehle wrote: > On 3/6/26 16:10, Juri Lelli wrote: ... > > + /* Start one cpuhog per CPU at max bandwidth */ > > + printf(" Starting %d cpuhog tasks at max bandwidth...\n", num_cpus); > > + > > + for (i = 0; i < num_cpus; i++) { > > + pids[i] = dl_create_cpuhog(runtime_ns, deadline_ns, period_ns, 0); > > + if (pids[i] < 0) { > > + printf(" Task %d failed to start: %s\n", > > + i + 1, strerror(errno)); > > + goto cleanup; > > + } > > + started++; > > + } > > Would it be okay to just have one task per max-cap CPU to make this pass on HMP? > Or something more sophisticated? > On HMP we should probably have max bandwidth hogs on big CPUs and then scale runtime (bandwidth) considering smaller CPUs capacities. Cannot quickly check atm, but that info (max cap per-CPU) is available somewhere in sys or proc, is it? Thanks, Juri