From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ms.lwn.net (ms.lwn.net [45.79.88.28]) (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 622ED23ED60; Sat, 26 Sep 2026 15:45:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.79.88.28 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790437520; cv=none; b=f/mHCMrEuF4tXhJeu2n91SdcN1U6kNXEK5IEi7C+Nhj1XstndpZB7xqcpIKya5zY6/e8XsW0dQH7Sou9xgxdAq8UCXbs9o/rFOzqUPTVcHE6lIWOl+WPJao2MzbE9fYpEK4WJprv5+q2uwuDxRTbvWy/W3EPOdkrKFEnpqEtPJI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790437520; c=relaxed/simple; bh=AGQQRfVn/LZC3bBxbuh5PVzchb9e6YqbQ12CpoBq9ik=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=GrthZu6DhyL/NR/wH10QQaUMEiZE9Ua0a831irqh5/OCSaHjsYKI9eNp3SCYPj6bMsGKn6697xEPcQzjtV2urV2CS6yPnV/ialQdEflTGQqA0KEb09OtJtEVgxLlGeelOZ9EmLkzvNUF0aBMSch2hMnHycBUCVgUQBr1OgPVizo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net; spf=pass smtp.mailfrom=lwn.net; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b=lklcf0Sa; arc=none smtp.client-ip=45.79.88.28 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lwn.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lwn.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lwn.net header.i=@lwn.net header.b="lklcf0Sa" DKIM-Filter: OpenDKIM Filter v2.11.0 ms.lwn.net 49157415B2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lwn.net; s=20201203; t=1790437518; bh=XOKkXjsyVICPpvg/s0jz2mX8l+l7Wcy1CQ2zuJfihiI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=lklcf0Sa+O9GwvgoH+jKyAbS2WAJ+Zm/Yc0v8U5Aa8aOyODvCri3CUF2VEQYZ3W5x KQQjuHfDNmBRq6yUNK+x/9UAABKbm5cVGz4LBsOYmH0UiBzfKmrKKAU6xDn6cxHZL/ gj311iZaQCeeK46kz4vkVP1hqGgZXzDOx6ESf0dptygS8ounfpV7xxIu5pE9RvY5j1 DDn+vE9HkAk4eVV7GqliPwYqiVXLwg2jy4BqjW0OTZK5Pfgc/o4f2SpipL2eekfGUz NntjxyKyf8p93ew07v8G+//BC2MvCDuwHAsr6N5ugeddAOVF8rwBBR7Yb6Ez1gm21c j47lVesS0zDUQ== Received: from localhost (unknown [IPv6:2601:280:4600:814::1fe]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 49157415B2; Sat, 26 Sep 2026 15:45:18 +0000 (UTC) From: Jonathan Corbet To: Quchaosheng Cc: Shuah Khan , Randy Dunlap , Ingo Molnar , Peter Zijlstra , Sebastian Andrzej Siewior , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, quchaosheng000406@163.com Subject: Re: [PATCH v2 1/2] sched/doc: add a preemption model overview In-Reply-To: <20260922083101.99685-1-quchaosheng000406@163.com> References: <20260922083101.99685-1-quchaosheng000406@163.com> Date: Sat, 26 Sep 2026 09:45:17 -0600 Message-ID: <87v77s2f02.fsf@trenco.lwn.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Quchaosheng writes: > The scheduler documentation describes the individual scheduling classes > and various tuning knobs, but there is nothing that describes the > preemption models themselves. The only place where they are documented > is the kernel-parameters entry for "preempt=", which explains the boot > time parameter but not the models it selects. > > Add Documentation/scheduler/sched-preemption.rst, covering the four > models, how a scheduling request is honoured under each of them, and > which of them can be selected at runtime. > > The overview follows the scheduling request: a wakeup makes a task > runnable, the scheduler decides what has to leave the CPU and sets > TIF_NEED_RESCHED or TIF_NEED_RESCHED_LAZY on it, and the preemption model > decides where that request is honoured. > > Assisted-by: LLM > Suggested-by: Sebastian Andrzej Siewior > Signed-off-by: Quchaosheng > --- I have applied these two patches. However: can you please send a followup with a suitable SPDX line for your new sched-preemption.rst file? Thanks, jon