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Thu, 29 Jan 2026 03:48:38 -0800 (PST) Received: from [192.168.1.166] ([185.168.96.228]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-481a5d55d3asm594825e9.6.2026.01.29.03.48.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Jan 2026 03:48:38 -0800 (PST) Message-ID: Subject: Re: [PATCH v2] sched/deadline: Reset dl_server execution state on stop From: gmonaco@redhat.com To: Andrea Righi Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Tejun Heo , Joel Fernandes , David Vernet , Changwoo Min , Daniel Hodges , sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org Date: Thu, 29 Jan 2026 12:48:35 +0100 In-Reply-To: References: <20260123161645.2181752-1-arighi@nvidia.com> <9b8c90b1-9247-4159-9bf6-72bd71bb74a2@redhat.com> <45e4dc7a-f261-46ec-8973-0fb8d1f7b0b9@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2026-01-28 at 14:41 +0100, Andrea Righi wrote: > Just to make sure we're testing the same thing, I'm currently using > https://git.kernel.org/pub/scm/linux/kernel/git/arighi/linux.git, > branch > scx-dl-server. >=20 > I'm running this test inside virtme-ng: > =C2=A0 $ vng -vb --config tools/testing/selftests/sched_ext/config > =C2=A0 $ vng -v -- tools/testing/selftests/sched_ext/runner -t rt_stall Well, that's a fun one, I could reproduce the same failure you described in vng on another x86 box. The arm box (bare metal) I used initially still passes just fine all 4 iterations of the test. On the x86 box (vng) I tried different orders of iterations (where the original is fair-ext-fair-ext) with and without the ext server active. No ext-server: the ext iteration fails and breaks also fair (unlike the arm64 box where the fair was intact) ext-server active: a sequence fair-ext breaks both (like you observe). I don't have time to look further into this right now, but it looks like an interesting pattern. Thanks, Gabriele