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Mon, 26 Jan 2026 07:11:48 -0800 (PST) Received: from somecomputer ([213.208.157.38]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4804d8a5c32sm343194095e9.11.2026.01.26.07.11.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 07:11:48 -0800 (PST) From: Richard Weinberger To: Richard Weinberger , xenomai@xenomai.org, upstream+xenomai@sigma-star.at Cc: Jan Kiszka Subject: Re: [PATCH] Allow changing CPU affinity of RT kernel tasks Date: Mon, 26 Jan 2026 16:11:46 +0100 Message-ID: <3016173.h6DGQjDypG@nailgun> In-Reply-To: <29de15c3-4d96-4194-9cbf-c362e9e83698@siemens.com> References: <20260126125701.21000-1-richard@nod.at> <29de15c3-4d96-4194-9cbf-c362e9e83698@siemens.com> Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdduheejleelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufffkfgjfhgggfgtsehtqhertddttdejnecuhfhrohhmpeftihgthhgrrhguucghvghinhgsvghrghgvrhcuoehrihgthhgrrhgusehsihhgmhgrqdhsthgrrhdrrghtqeenucggtffrrghtthgvrhhnpeetkeffffefgfeuieeivdejhfevfffghfeuffduheduuefhjedugffgleefgffffeenucfkphepvddujedrjedtrddujeekrddvuddupddvudefrddvtdekrdduheejrdefkeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpedvudejrdejtddrudejkedrvdduuddphhgvlhhopehsphhoohhlrdhmrghilhdrghgrnhguihdrnhgvthdpmhgrihhlfhhrohhmpehrihgthhgrrhgusehsihhgmhgrqdhsthgrrhdrrghtpdhqihgupeeuhfegieffgeefffefhfdpmhhouggvpehsmhhtphhouhhtpdhnsggprhgtphhtthhopedupdhrtghpthhtohepgigvnhhomhgriheslhhishhtshdrlhhinhhugidruggvvh On Montag, 26. J=C3=A4nner 2026 15:28 'Jan Kiszka' via upstream wrote: > This is one issue with setting the affinity "from outside", > asynchronously. The other is that it will always imply a migration of > the kernel task, thus a phase of non-RT. If someone forgets about this > and sets the affinity at the wrong time, it can ruin RT workloads. I assumed this is known and expected since changing the CPU affinity of use= rspace tasks as the same implications. > This tuning gap for RTDM task is rather old. I was already considering > to add an explicit affinity API to RTDM to set this from the driver. > That would allow to set the affinity early, right after task creation > and before the driver signals it is ready. Risk of such an interface is > that people start to hard-code the affinity into the drivers, rather > than making it configurable to userspace. Well, the goal of my patch is improving the situation to match userspace semantics. People expect that sched_setaffinity() kinda works. Thanks, //richard =2D-=20 =E2=80=8B=E2=80=8B=E2=80=8B=E2=80=8B=E2=80=8Bsigma star gmbh | Eduard-Bodem= =2DGasse 6, 6020 Innsbruck, AUT UID/VAT Nr: ATU 66964118 | FN: 374287y