From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 347EB387346 for ; Fri, 2 Oct 2026 12:45:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790945149; cv=none; b=rPvQzHgdwhF9sfFaU5C+H5SWgUzVi9n1kZr5cBGE6T1E5qEV0rL8Bq8BEg/SplJETinL+MceUjfahCFB4zQT+727tlYljvPzSwmQWhsCpzP7NKvkZ7RVVuRs7dj9lYMlSnSl2ioOtNP8WJy+xNCZZ+a2GmB+dX54NWrCASACMEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790945149; c=relaxed/simple; bh=6o9z390FSaXvtvYhDMYQXh3e4g3IXqp/50zPZ8SIe88=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Hp2/AkxX9GFwaVndqHg92dhdQ82/s6zFcAyIPRpQjdjRr9mQrJCzVIimhOAGQ2x2tUGqzqKWCKxte169EiF9LnPSSXKg/5QLGvvuWJmcou04cwWqlCvZkgXXxDFlGZ0yZaJt2672iF8UR/O0cVACYI7yaWL2BO7jV1Dsh+SNlaA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=Kvf4PQ/2; arc=none smtp.client-ip=80.241.56.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="Kvf4PQ/2" Received: from smtp202.mailbox.org (smtp202.mailbox.org [IPv6:2001:67c:2050:b231:465::202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519MLKEM768 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4hx7ml42xBzMl31; Fri, 02 Oct 2026 14:45:43 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1790945143; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=st2DE0l2eDcABWROMrXPJiQnFfgtYr1s5dyIvrcpjGg=; b=Kvf4PQ/28f8mxMjw2r6fLebF5wlWIqxvdefcUAhMZu8SlT94ra2cxxWNDjbnfP12bk+Tr2 5MarOrhydAtqi9b/axVM7GrupGrROrADPXRJ/3A0JVQ6DgJaYjDAG1ujALXztCTf42xwHk T0yLZ6jbh6ZEbk1CTMQf6SsWTuZuJT/QA2tjN+xJRvvYbIsfQSvUAE6TvtcdIOnegRF5ht mzQoU6rL3qoadxqRJQZtlrBZRQhI4C3zJpseUHn8pqG9zZSzwYJUbxTTZHGC3id7tBLRLu 7BNVXePV48MlA5BI7qXld4lN7DjR8XNBs8k5v3Qb1klvM+3uhwd60AmFFWlwQw== From: Tor Vic To: peterz@infradead.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, kprateek.nayak@amd.com Cc: linux-kernel@vger.kernel.org Subject: [RFC PATCH 0/2] sched/fair: Remove tunable scaling Date: Fri, 2 Oct 2026 14:45:36 +0200 Message-ID: <20261002124538.79658-1-torvic9@mailbox.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-MBO-RS-ID: 634eb3598d433251138 X-MBO-RS-META: zoscx7q6dbzrtbqgsn84w8c4duznsozb This series removes the scaling of tunables, which was introduced around Linux 2.6.33. I split this into two separate patches: The first removes the "none" and "linear" scaling which are likely not used much and have limited usefulness, as one can always set sched_base_slice through debugfs. It keeps the logarithmic scaling which is already the default. The second removes the entire scaling mecanism and sets a fixed sched_base_slice of 2 milliseconds, a value which has been chosen somewhat arbitrarily. Currently, the base_slice multiplied by the log2 factor can take the values of 0.7 (1 CPU), 1.4 (2-3 CPUs), 2.1 (4-7 CPUs) and 2.8 msecs (8+ CPUs), so it seems that the new value of 2 msecs is a sane default, which I also use on my consumer x86_64 machines. However I'll leave that open for discussion. Note that the base_slice value has changed quite often over the years, lastly in 2025 [1]. The series applies to 7.3-rc5, and is build- and boot tested on a measly 2C/4T Skylake machine. I marked it as RFC because I don't know whether these changes are actually wanted by the sched people - and because I'm not a developer. It does however remove quite a lot of code. [1] commit 2ae891b826958b60919ea21c727f77bcd6ffcc2c Tor Vic (2): sched/fair: Remove the 'none' and 'linear' scaling of tunables sched/fair: Remove sched_base_slice scaling altogether include/linux/sched/sysctl.h | 7 ---- kernel/sched/core.c | 1 - kernel/sched/debug.c | 52 ------------------------ kernel/sched/fair.c | 79 ++---------------------------------- kernel/sched/sched.h | 5 --- 5 files changed, 3 insertions(+), 141 deletions(-) -- 2.55.0